[leeklm]

As noted in my earlier post, I installed a full 3" system in the 68 bird with qtr exit. Overall I like the setup, but the 3" tip leaves virtually no room for error when exiting between springs and lower qtr panel. In addition, the car has an obnoxious resonance at light acceleration, which clears up once cruising steady or under heavy throttle. Some of this is due to solid body mounts and frame connectors, lack of rubber suspension bushings, etc. Maybe even drive train, but it feels great at the track!

To provide clearance, my thought was to cut about 8" length or so off the tail pipe, install a 3 to 2.5" reducer and then a chrome tip. This will be cheap enough to try, but curious if anyone has tried choking the tail pipe down like this? Did it have any funky results to the exhaust tone?

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[64speed]

I am interested in this question too because I plan to run 3 inch exhaust all the way to the back of the car but I am in love with the 64 GTO tail pipe splitters which are 2 1/4 inlet. My muffler man says he can stretch the inlet to slip over the 3 inch pipe but I’m worried about the 2 1/4 tip being a choke point.

[bendutro]

http://www.pontiacstreetperformance..../exhaust2.html

[leeklm]

So I ordered up a couple of $9 2.25" chrome tips, 3" band clamps, and a 3-2.25" reducer. Welded the tips to the reducer, then clamped on to tail pipe.

The chrome tip looks good, and of course provided better clearance than the 3" pipe. No noticeable difference in exhaust tone.

Being the exhaust gases are pretty cool by the time they reach the tip, I doubt there will be any noticeable performance difference. I plan to run at the track this wknd. If I see any difference in my ET, I can easily remove the tips for a comparison. Who knows, maybe an increase in exhaust pressure will increase my 60ft time, but I wont hold my breath

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[amcmike]

Little surprised the exhaust tone was unaffected, but it is only the tips, not the whole tailpipe. Let us know how it works out at the track. Great experiment.

I was considering doing the same on my Firebird, since the tailpipe exit clearance is tight between the leaf spring and the quarter panel. But right now I have bigger issues to address.

[Formulajones]

I do this fairly often on either a car I need a stock appearance with, need more clearance, or simply need to tone the exhaust note down a bit.

Generally speaking, reducing the tail pipe size or even just a short section of it at the rear of the car doesn't have a huge affect on performance. By the time the exhaust gasses reach that far back, they aren't as hot and aren't moving as fast. Been a lot of testing in that field with some mixed results but the general consensus is the same.

I've done it with customer cars as well as my own.

My wife's Z runs a Pypes SGF70 transverse system. 2 1/2" diameter with X-pipe and 2 1/2" tails. No drone and the car sounded fine, but just a pinch too loud for her. I also didn't like the chrome tips Pypes supplied for this system because they aren't bent correctly and don't exit like the factory tips should. So I removed the 2 1/2" tails out of the mufflers that are about 18-20" long on this system, and installed factory 2" tails with correct tips that exit correctly (they are all one piece) Not only did it complete the look I wanted, but it also toned the noise level down to a point my wife is extremely happy. It didn't affect the performance of the car at all, matter of fact it didn't even change the readings on my wide band.

Here is the car with the 2 1/2" tails
https://youtu.be/5dTNw93VPEQ

Here is the car with the 2" tails
https://youtu.be/IZ0HlEY7b74

It basically took the really deep tone out of it, which improved the in car sound significantly to the point it's much more pleasurable to drive.

Since you're just doing tips Leeklm I doubt you'll notice any difference in sound or performance. I've used small reducers just at the tip for correct exhaust tips on a bunch of cars I've restored just to get the correct appearance at the back of the car. Works fine with no ill affect. Matter of fact I prefer it over the alternative of running a complete correct crush bent exhaust system from Gardner that would really choke the car. I like performance improvements with stock appearances

[leeklm]

made it to the 1/4 mile yesterday, and car was in the 10.7's at 125mph with or without the 2,25" tips. Made no noticeable difference.