That is a good point. I only did not want to dump them before the axle was due to the fact that I have heard that any time you idle the car - say at a light or warming it up, it fills the cab of the car with exhaust fumes.

I would like to hear from all you guys whohave done it and if you have experienced this problem or not. I mean hell it would cost 1/2 as much as going over the axles and would be less restriction!

Thanks

Paul

 

Its a "track only" car, but has been driven on the street. Exhaust system consists of a pair of Borla XR-1 shorties on the header collectors, nothing else. I have not noticed any problems with exhaust odor in the car, either on the street or at the track.

Out local track now requires that all exhaust systems end PAST the rear edge of the door, and has a noise limit of 90dB @ 100-ft under full power, so I'll be adding a short length of 3" pipe and a 90-deg turndown with noise reduction cone to each side.

Here's what a Formula looks like without exhaust tips.

 

I get a big whiff of exhaust about 50% of stoplights i come too, and i'm exiting out of the rear (not duals). It seems a lot worse on the hot days though, but i guess if there was a breeze it wouldn't be so hot! I thoguht that was a given that if you don't run a cat u'd catch some fumes.

There is someone on this board with duals running both pipes over the stock location. I think it might be a female actually. Don't know exactly what to search for though so i couldn't come up with it.

 

I've been talking to a really good friend of mine who has been doing exhaust work for 16 years and he told me that to run true duals on my car all the way back and over the axle out the rear wouldn't be expensive but the only thing that would come of it would be dual pipes, he said i would get the same performance with a cat back. The duals would only sound different but not make the car any faster or have any other real significance. Just my 2 cents.

 

My duals stop at the axle and I have yet to get fumes. I have had them for about 3 months and my car is a convertiable. I also left my muffler and stock tips hanging back there just for looks and so the police would think I had a full exhaust. And it is my only car and gets driven proably to much

 

Both my car, and our shop car (when supercharged), had dual 3in off the headers, into a 3in X-pipe, which then reduced to dual 2.5 over the axle and to the bumper.

My car made over 600rwhp with that setup, and the shop car made over 700rwhp.

Exhaust cools as it travels further from the engine, taking up less space and allowing pipe diameter to decrease without restricting flow.

 

I wouldn't listen to that guy ^ , He's got his tire pressures listed with his dyno results like it's gonna help.....








Bwhahaha jk
mmmmmmmmm 700 hp!

And just so this post is on the thread topic. I agree with the above statement that the pipe diameter isn't as critical towards the end, but i would still run 3" all the way back if i was spending the money on that (i wanted to but i'm too poor and got a 2OTL cuz i didn't want an under the car exit).
There were two guys with identical 350 monte carlos, 1 had 2.5" duals, the other 3" duals. The three inch where where deeper at idle and stuff. Almost made it seem quiter it was so nice and deep. WHump WHump Whump...... then the thing would just scream when he got on it. Both sounded great though.

 

You know what is cool.. Look at eth exhasut in the new checy high performance.. It dumps on the side like nascar...

 

There was a girl named April Stiles who used to post here a lot. She had the dual pipes running over the rear axle, and had either removed the panhard rod brace completely, or radically modified it to allow the drivers side pipe to go over the axle. She had some great pics on her website, but a "search " turns up nothing and the old links don't work.

Just remember... the world's quickest LT1 (3,900# convertible, 9.04@155) ran into the very low 9's with a 4" Mufflex catback. He only removed it just before he ran the 9.04, and only because he wanted to save the 50# that the Mufflex weighed. They dyno'd the car, Borla shorties on the LT's, and 90-deg turndowns, and it made the same HP as it did with the Mufflex. If the 4" Mufflex can handle 1,125HP, it can't be that great a restriction... .