Dan12

Has anyone heard or tried to remove the cats from an OEM sytem. I’m saying just remove the cat material and reinstall the exhaust?

I have the opportunity to buy an OEM exhaust for 250 to modify while I keep my original in case I need it.

I also see a Milltek selling for 1500 or so with 100 CEL cats. If I bought new I’d go with an X pipe design so I’m not sure if the Milltek would sound much better than an OEM with the cats removed. Are the older exhausts now considered obsolete compared to the better sounding xpipe designs?

Does anyone have a sound clip of a decatted OEM exhaust so I could compare it to the Milltek?

Thanks

NickS

I'm not sure if there are test pipes with O2 bungs even available that fit to the OE exhaust but no, I have personally never heard (read) of anyone doing this.

Dan12

I didn't mean removing the cans, just the cat material in the cans and converting it into a catless system. CEL would come on so the next question would be if the software upgrades would correct that.

Like I said $250 for a spare exhaust might be worth a try but if the drone is awful or it just doesn’t sound right then aftermarket is the only way.

was hoping someone tried this already.

Team Plutonium

A tune will take care of the CEL. The whole process sounds a bit ghetto to me though... LOL. removing the material alone has the potential of making your car just sound like crap - but only one way to find out. Depending where you live the CEL is only half your problem, if your state has a sniffer test you;d have to swap out the exhaust (no big deal though), also some tunes will still store two fault codes within the DME - most states fail you with two codes. Last, if you get pulled over you can be in a world of hurt (depends on the cop or trooper), removing the cats is a federal offense carrying a $10K fine. I'd wager that 911 turbos are prone to be pulled over in the first place, add the noise (it will be loud), and then the smell (unless the officer is retarded) you'll get more than a fix-it ticket.

Having said that, I ran fully cat-less with my SC M3 a few years back, I wouldn't do it again, the stress is not worth it the 20-30hp you might pick up. Just my two cents...

cretinx

The Honda forums did this (because gutting cats is common practice) and found on the dyno that a gutted cat produced so much additional turbulence in the exhaust that the cars lost power.

Either get some test pipes, get a welder to make you a nice custom solution (cheaper than you think . . . . cheaper than any aftermarket solution actually, no Porsche tax) or just run high flow cats.

You'll never pass inspection without cats, and it's also a violation of Federal law so I hope you don't plan to drive on the streets.

Dan12

Looks like I'll go with an aftermarket. Just thought a $4K exhaust should be able to produce a better sound if modified correctly? Doesn't sound like its worth the effort.

cretinx

$4,000 exhaust? Are you smoking rocks?

You can get a fully custom, extremely lightweight steel weld-**** quality exhaust for $1,200-$1,500.

Dan12

I have never tried to smoke rocks. I imagine it would be difficult to get them lit.

Other than a local custom shop are there any places that specialize in what you say and can build and ship a system?

voodoochild997tt

Look around the site it's been talked about a lot..
Im from israel and Was thinking of doing it myself..
Can't upload more pics that I've collected for the mod for some reason

https://rennlist.com/forums/996-turb...ke-inside.html

http://www.6speedonline.com/forums/9...e-exhaust.html

All true what been written in here but still a waist of a killar system..

Few things you should know:

1st,there is more then that one cat on each side,there is one in the muffler as well!! (4 all together in the car..) and without cutting the muffler open cant be reached..
(Which this exactly what fvd,ruf,techart do with there retro fit systems,pull old ones and putting one free flow in canister..)

2.pretty sure they have 600cel each side and the ones in the canisters are smaller 200cel then the muffler ones400 making the simple gutting not really reasonable without cutting it open

3.The canister big size was built to house a cat and without one the drone will be unbearable so leaving this one in or replacing for a more free flow one is a must..

One more mod possible is drilling a straight 2" hole trow the tailpipes towards the turbo basically bypassing the muffler and bay leaving the first cat in,you stay legal..

Me,I would tray to open that sucker up and weld one 100cel in..
Hope I've helped
Cheers
Oren

TT Surgeon

Here you go, they have 2 cats per side. The other big points of obstruction are the clam shells and tertiary pipe diameter.

Dan12

Thanks for the input guys, gives me some things to think about.

Probably end up buying a used real system in the end but with all this snow around I just might experiment a bit.

I like the idea about using 100 cel cats but if I go that far it may be worht making an xpipe design. Would have to start from scratch and try to use the OEM sytem only for measurments.

I only drove my Turbo 3 times before I had to put it away.

We'll see what happens.

cretinx

Those people will charge the "Porsche tax".

I strongly suggest you ask members of the PCA where they get welding done for things like cages, exhausts, etc and discuss the details with said welder of getting a custom setup.

You will drop a ton of weight, make some meaningful power, and get things done exactly the way you want them, with a human being to hold accountable (and form a relationship with for future projects).

You'll also be support small businesses.
'Murica.

Dan12

I'm starting to source some cats, mufflers and an xpipe. I think I can put together a nice system after taking a close look.

Does anyone have suggestions for cats or mufflers? I'm not sure if I'm going with four mufflers or two, I've seen both. They need to be small so four may be needed.

Other option would be only two mufflers for go with 200 CEL cats vs 100. i've got two months to figure it out.

flyjets

TT Surgeon there have been a few Race shops tell me that you can use a 2" hole Saw up the exhaust wall and it sounds good and performs slightly better. From you photo I can't visualize where that might be any thoughts?

The rest of you guys talked about this.............. U know there is Fire out the exhaust when you lift off the Throttle with this.

http://www.ebay.com/itm/3-Turbo-Out-...98f218&vxp=mtr

Ian

John D II

Hi Dan,

After reading this, all I can say is be careful - the EGT's on the 997TT are extremely high and only very specialized cats will survive more than a week or two...or a couple of months. It's not like you can just put any inexpensive cat on a 997TT and build a cheap system. It won't work for long and there is an inherent risk that comes along with it.

If you want a proper X-Pipe system that has been developed to achieve a great sound, PM me and I will be glad to discuss it with you and give you a good deal. No huge Porsche tax. Although more expensive than a pieced together home project like you are describing, the majority of the cost is actually in the quality components (cats being a big one) and skilled tig welding. Not to mention, we have tested our various 997TT systems for sound attributes and can recommend the proper model to suit your taste/goals. And we have a sound guaranty. Just some food for thought.

Knowing what I know and seeing the road you are going down, I have a feeling I know how it is going to end up and I am honestly pointing this out to save you what I feel will result in a lot of aggravation and most likely disappointment in the final result. As an exhaust manufacturer, I know it takes more than one attempt to get it dialed in right and that is more time and more money when building a one off system like you describe.