Calling all exhaust experts

[noelb]

I have a standard exhaust on my Burb. The down pipe is straight and about 2.5 inch OD. I have a CAT and standard Muffler with 2.75 inch pipe. How much difference will it make if I install a 3 inch Straight Through Muffler (6X10X20 inches.) Can do this for about $200 USD the only other option I have is to ship a system from the States to Australia which may be cost prohibitive.(450 USD plus Shipping?)

Also how blocked is the CAT likely to be with 135k miles. The exhaust place with not let the vehicle out of the workshop without one - Huge Fines apply.

By the way Priced Genune CAT at $1500 USD:eek: - can you believe that. They were however happy to sell it for half that price as it was old stock--not likely they will ever sell it; at least not to this little brown duck!!!:p

[john8662]

I replaced the downpipe and had the exhaust shop "connect" my downpipe to the rest of the exhaust system. I had cut it short of course, cause there wasn't a CAT any more, musta slipped, or forgot to measure twice before cutting, anyways...

I didn't get any question as to whether there would be a CAT.

I really don't think your cat is that plugged, they usually are not, if the engine has had the turbo working on it most of the time and is not an EGR engine (which yours isn't).

I don't think you'll get much of a gain with just changing the muffler and leaving everything else alone.

my .02

[noelb]

Thanks for your 2c John8662. Some creative thinking going on.:D

[DennisG01]

You could hollow out the CAT, then push a straight pipe all the way through it, then weld the now empty cat to the pipe. ;)

[Warren96]

I would have to agree with John, I tried a test pipe for a short time with a straight thru like you described and couldn't measure any improvement. But the noise from the turbo drove me nuts: that whistling made it sound like a garbage truck. Not to mention the second looks from the police and motor vehicle inspectors( the agency who enforces the clean air rules ).Personaly i like the sound of the engine, not the turbo. Just my 2c.

[MTTwister]

I started with a 3" BD Down pipe - it has the flange to re-bolt up the CAT.

Then I cut the original exhaust pipe between the torsion bar fram member and the muffler ( where I could get to it. ) I got a 9" length of 3" pipe from an exhaust shop, with 2 3" clamps.

During the downpipe install, I removed the CAT and hollowed it out, then used the 3" as a slip joint to re-install.

Replacing the downpipe will probably yield the best results. Mine wasn't near as bad as the picture on Kennedy's tech page, but it wasn't straight and clean either.

EDIT - oops - disclaimer - not an expert. Also, recently added Kennedy's 3.5" after the Cat, sorta B-dized his full system, but oh well.