pcar964

Well you have me curious - I wonder if just removing the muffler (and leaving the muffler-side of the cat exposed) would be a close approximation of the muffler bypass...

Either way, I'm not too obsessed with weight reduction, just want to keep the car close to stock but get the easy/cheap hp gains that are available.

Y65MPH

The secondary muffler is actually very free flowing. The only way to get a real performance gain is to remove the cat. Removing the secondary muffler will save a little weight and with a G-pipe will add noise but not much performance.

pcar964

That seals the deal for me, I'll just be doing away with the cat and keeping the muffler stock. Does anybody know if the little miniature catalytic converter coming off the turbo is worth gutting? I assume there is some restriction there also...

cobalt

Actually 0 performance gains from removing the secondary although the cat and muffler combined do save nearly 50 pounds which adds to performance. You can feel the weight loss because of where it is removed. I agree the best performance gain is to remove the cat. Spool up is improved.

BTW go to off topic a plane crashed into the Hudson river a short time ago. I saw it coming down but didn't see it hit.

Metal Guru

Massive bird strike took out both engines. Fortunately there were no fatalities.

http://www.google.com/hostednews/ap/...zhzqQD95NRK0O0

911addict

The wastegate cat, does not restrict.
The only benefit of removing is the sound. You can pootle quietly around town off boost, but when you hit full boost your car will 'shout'. Ideal for stealth in traffic, and fun at speed. But pcar, sounds like you want stealth all round, so will be too loud for you. ;-)

pcar964

Wow, that is interesting. So does anyone know, percentage-wise, how much of the exhaust gas exits the right exhaust (from the muffler) vs the left exhaust (from the turbo)?

bogey1

nothing comes out the left side until your under boost.

pcar964

So I talked to a guy at my local Midas shop, he says if I bring in the catalytic converter, he can custom make, with the correct flanges, a straight pipe in stainless steel to fit where the cat went. Total cost under $100!! Am I forgetting something here, or is this a good option? What size should I have him make the pipe, 3"?

Mike Andrews

Pcar....

Gutting a stock converter is not as easy as it on some other cars. The core is metal not ceramic and getting the old stuff out of the can is not an easy task. It doesn't just break up like the ceramic ones.

I think there is a benefit to using the stock gutted pieces. The first is the fit and finish. Everything fits and lines up as it should and it all looks stock underneath. I despise the way some of these aftermarket parts fit. It pisses me off that they charge the money they do and the parts don't line up as they should/could. I just don't get it.

Anyway, your biggest performance benefit will be removing the cat. You can do this with a bypass pipe or with a gutted cat. BTW, someone else mentioned the gutted cat will have a funny sound (or something to that extent). I for one like the way cars with gutted cats sound. It has a unique sound, and I like it.

Removing the cat will make the car louder, but it's not that bad. You should probably get a ride in one before you go any further just to make sure it's not too loud for your tastes.

The second thing you can do is replace the secondary muffler. As a number of people have commented, there is not that big a performance gain in doing that.

I gutted my secondary muffler instead of replacing it as I want my car to appear stock and I want all the pieces to line up where they should.

The downsides of gutting the cat are the value of the cat and the weight. A bypass pipe will cost less than a spare cat and it would be lighter as well.

Good luck....

pcar964

Thanks Mike, that is why I'm thinking of having my local muffler shop just fabricate me a test pipe. It's not that complicated, just a pipe and two flanges - and I'm with you, I have NO IDEA how aftermarket tuners come up with those prices for a simple pipe - it's insulting that a person would be asked to pay $450 for standard 3-4" stainless pipe just because it's a Porsche.

911addict

Or spend a little more, and get a quality product for your supercar:
http://www.scart-exhausts.com/ang/de...php?produit=98

PS: no affiliation, just a very satisfied customer.

pcar964

Thanks for the link - but honestly I think it's outrageous to pay that sort of money for a straight piece of pipe. There is no performance gained by having a shiny, polished pipe with a brand name on it, over a plain piece of stainless pipe. The only difference is about $400 extra in my wallet going with the latter

Mike Andrews

Ok... this is exactly what I'm talking about. Why would they design/build/sell a piece with a flange with slots in it? Why can't it be like the stock piece and have the alignment correct so they don't need to put slots, or larger holes, to allow for adjustment/fitment issues.

911addict

Mike, don't see what you mean. It fitted perfectly.
Anyway that's me outta this thread, I spent a lot of time and money working out what's good for our cars and what's not worth scimping on. Personally I found butchering exhaust pipes a PITA.