gtbrandon

So I want to make my car sound a little throatier/deeper, and think a muffler delete is a good place to start. Yes, yes I can get a full exhaust system that will have less drone and be better but that's also $1,000 vs $100. I can always install the aftermarket exhaust if I don't like the results of the muffler delete. My question is, is there any expereince with a loss of backpressure due to removing the mufflers, and if so, has this caused any performance losses. It has been hard to find anyone who has done this on their Cayman/Boxster so I thought I'd post this up and find out.

Side note: If anyone is selling their aftermarket exhaust or headers, let me know as I'm looking for a good deal on a used set.

PorscheAddict

If you just want a little louder or throatier a muffler delete will drive you nuts - it will be very very loud. It would also be technically difficult since you would have to craft curved pipe to fit where the muffler was. Loss of backpressure will cause little to no hp increase/decrease, but bad flow (i.e., from a leak rather than just being free flowing) will decrease power.

If you have a 981 I'm selling a Fabspeed Maxflo you may be interested in: https://rennlist.com/forums/parts-ma...for-981-a.html.

jscott82

There is no such thing as "good" back-pressure... Any resistance to flow is bad...

The problem, is harmonics. OEM does a great job of modeling pipe lengths, chamber size, pipe diameter to achieve good flow. Simply pulling the muffler out and replacing with a piece of pipe, probably not going to do too much either way.

I have a Tubi system that was on my 987.1 when I got it. If you are interested.

gtbrandon

Did you run a muffler delete on your car, if so how did you deal with the intermediate pipe between the two mufflers? Also I'm assuming there would be no leaks from a clean weld, so I'm not seeing the issue?

Side note: Can you run a 981 exhaust on a 987.1?

gtbrandon

So I decided to go to a local muffler shop and see how much damage I could do with $100. I got rid of the rear mufflers (and secondary cats inside them) and replaced with a good ol' straight pipe. In my opinion it sounds great and could not be happier. Drone isn't terrible and for this price compared to a new or even used exhaust system, I think I came out on top. We will see in the coming days how this is on the highway but around town the sound is just right for me, and when I get on it...Oh man does it make me smile. Also an added benefit of weight reduction from those damn mufflers, must weight 20lbs each with the cats inside. Here's a video of around town and a few pulls, let me know what you think compared to your exhaust set ups.

PorscheAddict

Sounds pretty good for the price, but I suspect it will be pretty uncomfortable on the highway. My 981 with race headers and PSE in open is perfect to my ears, but MUCH more expensive.

billwot

Back pressure is an increase in pumping losses, and restricts the volume of the subsequent intake charge of air/fuel.

"Any resistance to flow is bad"

GregWormald

I think that maybe is too simple. I'm not an expert but the shop that worked on my motorcycle, who builds specialty racing exhausts as well a does custom work on road bikes, said that (for my bike) tuning and increasing the back pressure at the crossover tube between the cylinders would increase low end torque. Decreasing would increase high-rev power but I'd lose drivability at lower revs.

billwot

No, it really is not "too simple". But people often confuse "back pressure" with other exhaust variables like harmonics and tuning.

1) Back pressure is a parasitic pumping loss. It is an increased load on the piston which must be overcome during the exhaust upstroke.

2) Back pressure reduces the amount of spent exhaust gas that is cleared, so residual gasses remain in the combustion, and interfere with the inflow of a fresh air/fuel charge.

There is an exception to the "back pressure is bad" rule, however. Back pressure is important for 2 cycle engines. Because of the design and operation of 2 cycles, both the exhaust and intake ports are open simultaneously. Back pressure actually helps contain the fresh A/F charge, and prevents if simply flowing back out the open exhaust port. So exhaust tuning, harnessing the natural harmonics, is actually ver important for maximizing 2 cycle performance. And exhaust tuning that creates a venturi effect to actually reduce back pressure in an adjacent runner also increase performance in a 4 stroke engine, again, by actually reducing back pressure

medtech

Sounds pretty good to me!

Alan C.

What did the shop use for the tubing? I've seen shops use Aluminzed Carbon Steel for tubing on cars with 304SS. Not a good option.

digitalrurouni

I always thought the GT4 and Spyder were loud enough already. Frankly I even think they sound better than the GT3 motor. It's like when people say the 458 Speciale sounds better than the 458 I have to disagree. Something about those really high revs where the sound just goes all janky and harsh instead of sounding pleasant. Anyway I am probably in the minority but my question would be with the valves open these cars are freaking loud - with muffler bypasses wouldn't tracks black flag you if you cause of the decibels?

yadier713