AWE crossiver pipes
11-08-2011, 08:39 PM
#16
i did the AWE crossover pipes about a month ago...
Now it sounds more like a Porsche. Dont get me wrong... You will not hear crazy differences but the car definitely sounds better...
I liked the fitmet, i liked the weight reduction and according to other the car maybe have picked up a couple of hp...
See a couple of videos from my car to evaluate the sound...
it only has BMC filters and the AWE crossover pipes... Everything else is stock...
Now it sounds more like a Porsche. Dont get me wrong... You will not hear crazy differences but the car definitely sounds better...
I liked the fitmet, i liked the weight reduction and according to other the car maybe have picked up a couple of hp...
See a couple of videos from my car to evaluate the sound...
it only has BMC filters and the AWE crossover pipes... Everything else is stock...
11-09-2011, 12:51 PM
#17
Rennlist Member
Thread Starter
i agree. Unless the Gundo Hack sounds significantly better why not just go with a high quality aftermarket cross overpipes? From my research it does'nt seem like a hugh price difference.
11-09-2011, 01:26 PM
#18
Drifting
New guy 5 posts. Pay some respect to someone with a lot more 997 experience then yourself. The gundo hack is exactlly that a hack. Its amazing you were at the factory to see how they manufacture their sport exhausts in the rudimentary manner you suggest. I'm sure your muffler shop did an amazing job and you will never get an exhaust leak? Most feel great saving a few bucks. I'm happy for you, especially with all of those variables. Hat tip PTK Parks. Look at you all gussied up!
What is exactly is implied by a "hack" anyways? The crossover is usually done by a reputable muffler shop and it is simply fabricating a crossover pipe between the inlet and outlet - theres no magic to it (why dont we change the name to Porsche Sport Exhaust Not Done BY Porsche and Not Charged Accordingly)
Honestly, some guys want to put the OE PSE on and that cool but some guys dont see the valued added in paying 10x as much for the same sound and thats cool by me as well
And look!! I have more posts than you - there i said it!
11-09-2011, 01:27 PM
#19
Rennlist Member
gundo hack creates turbulance where in stock form you have nice direct flow. i do not like it at all.
bypass pipes instead of central muffler do reduce back pressure just a bit but compared to stock cats it is virtually nothing, so, i would not expect any major improvemnt from mufflers exchange.
bypass pipes instead of central muffler do reduce back pressure just a bit but compared to stock cats it is virtually nothing, so, i would not expect any major improvemnt from mufflers exchange.
11-09-2011, 01:32 PM
#20
Drifting
However my understanding is that to achieve comparable sound in the 997.2 (because of the 3rd muffler) you need the crossover AND sport mufflers (or the BS gundo hack). You are talking about changing out 2 parts on the 997.2 vs one on the 997.1
Enjoy, which ever way you go
11-09-2011, 01:35 PM
#21
Drifting
gundo hack creates turbulance where in stock form you have nice direct flow. i do not like it at all.
bypass pipes instead of central muffler do reduce back pressure just a bit but compared to stock cats it is virtually nothing, so, i would not expect any major improvemnt from mufflers exchange.
bypass pipes instead of central muffler do reduce back pressure just a bit but compared to stock cats it is virtually nothing, so, i would not expect any major improvemnt from mufflers exchange.
11-09-2011, 01:46 PM
#22
Rennlist Member
sport exhaust is designed to allow passage of as much air as possible with minimal resistance. it all matters when you get into 6K+ rpm zone.
so to add power in any naturally aspirated engine you need to allow more air to enter the engine and reduce back pressure on the exhaust side.
first critical element is headers where you need to have proiper diameter of the intake hole to control pressure in the cylinders - it cannot just spray into open air. usually people put there x51 headers on 997.1 cars, on 997.2 cars i have no idea. then you get cats - here on real sport car you would have a bypass, on a street legal car you go with 100 or 200 cell elements instead of stock 600 cell cats. 100cell cats usually trigger a CEL from post-cat oxygen sensors no matter what, 200cell cats may work fine with stock ECU. then you put on ECU flash that can use up all available air and shift timing ignoring strict emissions restrictions in the stock ECU program. it also ignores input from post-cat O2 sensors so it never throws a CEL.
so engine runs a bit hotter, spits out more junk in the air and gives you better performance at WOT.
but that reduced back pressure in exhaust reduces torque in low rpm range. so it is a trade-off and when we speak of such modifications it is typical to speak of 'curve' modification - you gain power at top but loose it down below.
mufflers change very little in this model. i had my car dynoed with fabspeed maxflo mufflers and then dynoed with stock mufflers - it had may be 4hp diff at all which is totally negligent. imho all that muffler business is just a waste of money. plus stock muffler sounds fine when you put in 200cell cat which is at least 2 times louder than a stock cat.
so to add power in any naturally aspirated engine you need to allow more air to enter the engine and reduce back pressure on the exhaust side.
first critical element is headers where you need to have proiper diameter of the intake hole to control pressure in the cylinders - it cannot just spray into open air. usually people put there x51 headers on 997.1 cars, on 997.2 cars i have no idea. then you get cats - here on real sport car you would have a bypass, on a street legal car you go with 100 or 200 cell elements instead of stock 600 cell cats. 100cell cats usually trigger a CEL from post-cat oxygen sensors no matter what, 200cell cats may work fine with stock ECU. then you put on ECU flash that can use up all available air and shift timing ignoring strict emissions restrictions in the stock ECU program. it also ignores input from post-cat O2 sensors so it never throws a CEL.
so engine runs a bit hotter, spits out more junk in the air and gives you better performance at WOT.
but that reduced back pressure in exhaust reduces torque in low rpm range. so it is a trade-off and when we speak of such modifications it is typical to speak of 'curve' modification - you gain power at top but loose it down below.
mufflers change very little in this model. i had my car dynoed with fabspeed maxflo mufflers and then dynoed with stock mufflers - it had may be 4hp diff at all which is totally negligent. imho all that muffler business is just a waste of money. plus stock muffler sounds fine when you put in 200cell cat which is at least 2 times louder than a stock cat.
11-09-2011, 02:06 PM
#23
Drifting
sport exhaust is designed to allow passage of as much air as possible with minimal resistance. it all matters when you get into 6K+ rpm zone.
so to add power in any naturally aspirated engine you need to allow more air to enter the engine and reduce back pressure on the exhaust side.
first critical element is headers where you need to have proiper diameter of the intake hole to control pressure in the cylinders - it cannot just spray into open air. usually people put there x51 headers on 997.1 cars, on 997.2 cars i have no idea. then you get cats - here on real sport car you would have a bypass, on a street legal car you go with 100 or 200 cell elements instead of stock 600 cell cats. 100cell cats usually trigger a CEL from post-cat oxygen sensors no matter what, 200cell cats may work fine with stock ECU. then you put on ECU flash that can use up all available air and shift timing ignoring strict emissions restrictions in the stock ECU program. it also ignores input from post-cat O2 sensors so it never throws a CEL.
so engine runs a bit hotter, spits out more junk in the air and gives you better performance at WOT.
but that reduced back pressure in exhaust reduces torque in low rpm range. so it is a trade-off and when we speak of such modifications it is typical to speak of 'curve' modification - you gain power at top but loose it down below.
mufflers change very little in this model. i had my car dynoed with fabspeed maxflo mufflers and then dynoed with stock mufflers - it had may be 4hp diff at all which is totally negligent. imho all that muffler business is just a waste of money. plus stock muffler sounds fine when you put in 200cell cat which is at least 2 times louder than a stock cat.
so to add power in any naturally aspirated engine you need to allow more air to enter the engine and reduce back pressure on the exhaust side.
first critical element is headers where you need to have proiper diameter of the intake hole to control pressure in the cylinders - it cannot just spray into open air. usually people put there x51 headers on 997.1 cars, on 997.2 cars i have no idea. then you get cats - here on real sport car you would have a bypass, on a street legal car you go with 100 or 200 cell elements instead of stock 600 cell cats. 100cell cats usually trigger a CEL from post-cat oxygen sensors no matter what, 200cell cats may work fine with stock ECU. then you put on ECU flash that can use up all available air and shift timing ignoring strict emissions restrictions in the stock ECU program. it also ignores input from post-cat O2 sensors so it never throws a CEL.
so engine runs a bit hotter, spits out more junk in the air and gives you better performance at WOT.
but that reduced back pressure in exhaust reduces torque in low rpm range. so it is a trade-off and when we speak of such modifications it is typical to speak of 'curve' modification - you gain power at top but loose it down below.
mufflers change very little in this model. i had my car dynoed with fabspeed maxflo mufflers and then dynoed with stock mufflers - it had may be 4hp diff at all which is totally negligent. imho all that muffler business is just a waste of money. plus stock muffler sounds fine when you put in 200cell cat which is at least 2 times louder than a stock cat.
My point remains, if all you are looking for is sound, the gundo is a legitimate way to achieve this at 1/10th the cost. No more no less
If you want an on/off switch and OE equipment, then buck up by all means
11-09-2011, 02:36 PM
#24
Rennlist Member
i never saw one. but i do not think it would be decreased by much with gundo hack alone considering all the rest was left stock.
also - this was a good thread for 997.2 cars i think.
https://rennlist.com/forums/997-foru...dk-tuning.html
also - this was a good thread for 997.2 cars i think.
https://rennlist.com/forums/997-foru...dk-tuning.html
11-09-2011, 03:30 PM
#25
Drifting
i never saw one. but i do not think it would be decreased by much with gundo hack alone considering all the rest was left stock.
also - this was a good thread for 997.2 cars i think.
https://rennlist.com/forums/997-foru...dk-tuning.html
also - this was a good thread for 997.2 cars i think.
https://rennlist.com/forums/997-foru...dk-tuning.html
Or that the effect of a change to any muffler set up alone (including PSE) has no HP effect to speak of
11-09-2011, 03:41 PM
#26
Rennlist Member
just like i said - i do not like it. 
i would not do it to my car. to speak more i would need to do it and measure it, so, i keep it at level of personal preferences.
i would not do it to my car. to speak more i would need to do it and measure it, so, i keep it at level of personal preferences.
11-09-2011, 04:50 PM
#27
Drifting
11-09-2011, 05:18 PM
#28
I think i finally narrowed it down to upgarde my exhaust to AWE corssover pipes for my 09 C4 Targa. I found a local indie for the install and the price seems fair. The main reason for the mod is for a more agressive sound. Seems to be a touchy subject weather or not you really gain or loose HP. One concern I have weather or not this mod will cause any CEL or inspection issues. Will the mod void my warentee? TIA for any comments or suggestions.
11-09-2011, 11:44 PM
#29
Race Director
gundo hack creates turbulance where in stock form you have nice direct flow. i do not like it at all.
bypass pipes instead of central muffler do reduce back pressure just a bit but compared to stock cats it is virtually nothing, so, i would not expect any major improvemnt from mufflers exchange.
bypass pipes instead of central muffler do reduce back pressure just a bit but compared to stock cats it is virtually nothing, so, i would not expect any major improvemnt from mufflers exchange.
Gundo hack is not the same exhaust flow route as PSE.
11-10-2011, 08:53 AM
#30
Rennlist Member
Thread Starter
Gellie, bottom line is that cross over pipes to replace the center muffler will improve the exhaust note a little but for many this improvement is not enough without doing either (1) PSE, or (2) other after market side mufflers (eg Tubi) or (3) the Gundo Hack. I have sharkwerks crossover pipes and like them but would prefer more agressive sound so am contemplating Gundo Hack. If you are seeking increases in HP, none of these aforementioned combinations will produce much unless you also change the headers and the CATs. I think that if you go this route you may need to remap the engine and may run the risk of invalidating your warranty. So if you are a simple street driving man (like I) start with the cross over pipes. Can't go wrong there IMO.