3 inch exhaust

[Metako]

Has anyone managed to squeeze in a 3 inch exhaust over the 505 rear crossmember? I'd like to get a new exhaust (or at least cat back) soon and it looks like a very tight squeeze. Dont want to go side-exit as in the article in "505 tech". If 3 inch wont work I have this idea of going from a 3 inch front muffler to a Y adapter to 2 x 2.25 inch pipes (slightly more area than a 3 inch pipe) which run over the rear crossmember, one on top of the other, and then to another Y adapter and into a rear 3 inch ressonator/muffler. Any thoughts?

[V-M]

Has anyone managed to squeeze in a 3 inch exhaust over the 505 rear crossmember? I'd like to get a new exhaust (or at least cat back) soon and it looks like a very tight squeeze. Dont want to go side-exit as in the article in "505 tech". If 3 inch wont work I have this idea of going from a 3 inch front muffler to a Y adapter to 2 x 2.25 inch pipes (slightly more area than a 3 inch pipe) which run over the rear crossmember, one on top of the other, and then to another Y adapter and into a rear 3 inch ressonator/muffler. Any thoughts?

Nope... I have 3" from turbo to that narrow place and from there its 2,5" on last muffler (standard) and out is standand muffler...

See ->

I don't see any reason or benefit to make any bigger... from power perspective, gas cools down enough in that 3" pipe to flow that 2,5" and mufflers part. IMHO

V-M

[Metako]

Interesting V-M. Do you have a 3 inch cat too? After reading your reply I did some googling and found the link below. It seems that 3 inch front and 2.5 inch rear section may give better performance than 3 inch all the way, although I'm not 100% convinced yet as the guy says "all I changed was the rear pipe diameter and a TUNE[!!!!]". I suspect the tune had something to do with the improvement. Before this I'd always read that bigger is always better as far as exhaust size for a turbo car. But I dont think the std Peugeot mufflers flow too well V-M. Are they straight-through or baffled?

http://www.rexnet.com.au/forum/index.php?showtopic=77019

[Justice]

It won't take long for these cars to reach 25. 6 years if you are unlucky. After that you can take off the cat. At least here in Texas, where 25+ year old cars are emissions exempt. The better a turbo exhaust is at getting rid of the exhaust fumes, the faster the turbo will spool as it is driven by exhaust fumes! So yeah, open pipe FTW!

You will generate some back pressure going smaller in the rear. But it's better than the other way around. Those ricers with them fartcans just loose torque doing that.

[V-M]

We don't need to have cat on cars older than -91 :-). Like I said flow exhoust gas cools down so much at it goes smaller pipe size in end. And outlooking is like untouched ;-)

V-M

P.S Cat is no prob it only costs 90€ and its easy to add there if needed.

[Metako]

I definitely plan to keep my cat for environmental reasons and its been show in many tests that a cat is a very small restriction, much less than most mufflers. I guess at my current power level a 2.5 inch would be fine but one always has plans to increase the power one day . Here is an interesting link to a discussion including a guy who says he is an engineer and Garrett-trained who reaffirms that the bigger the exhaust on a turbo car the better, and that a bigger exhaust will improve low-down torque with a turbo (unlike NA cars which need some backpressure). Seems to go against the info in the previous link.

http://www.rx7club.com/showthread.php?t=757038

[V-M]

Under 400hp eaven 2,5" enough... (atleast db should be that size) Of cause if there is space... allways bigger is better.

Originell pipe is 2,1"...

V-M

[Bean]

I was thinking of running a muffler that has 3" in, and 2 x 2.5" output, that way it elimnates the need for a "Y". You can then run the two pipes on either side of the torque tube and over the rear cross member.

I'm also going to remove the tire carrier and have the exhaust run straight out the back. Not sure if I'd keep it dual, or run it into another muffler that has 2 x 2.5" inputs and a 3" out. (Same muffler as the front just reversed.)

Since the turbo quells a lot of the sound anyway - one muffler might be enough, so it'd be less weight to just run the two pipe straight out the back... (Planing on routing it through the rear panel and through the rear bumper... That or turn it 90 degrees down if it's too loud. It'll all be tucked up under the car to keep it stealthy looking.

Rabin

[Metako]

I thought of the same type of muffler Bean but if I have the two exit pipes on top of each other on the same side of the diff then it might be easier to have the two outlets on the Y vertically stacked also, rather than horizontally which would be the case in a single entry/twin exit muffler. The muffler's a good idea if you want to run a pipe either side of the diff though. I was running just one muffler for a couple of days when my rear ressonator fell off (I run a cat, a front muffler and a rear ressonator) and the noise was just too much. It made me feel very conspicuous especially to the police-I prefer to blend in more. My front muffler's only about 12-13 inches long though, and straight-through so a longer or baffled one may be enough.

[Bean]

I thought of the same type of muffler Bean but if I have the two exit pipes on top of each other on the same side of the diff then it might be easier to have the two outlets on the Y vertically stacked also, rather than horizontally which would be the case in a single entry/twin exit muffler. The muffler's a good idea if you want to run a pipe either side of the diff though. I was running just one muffler for a couple of days when my rear ressonator fell off (I run a cat, a front muffler and a rear ressonator) and the noise was just too much. It made me feel very conspicuous especially to the police-I prefer to blend in more. My front muffler's only about 12-13 inches long though, and straight-through so a longer or baffled one may be enough.

I can't picture enough room for "stacked" pipes to go through on the same side. I ran a 2.25" exhaust on my 504 V6 years ago and the exhaust shop had a bugger of a time fitting a single pipe through. Even on the turbo and V6 cars - it's a pretty tight fit.

Unless one goes over and one goes under - that might work. Or if you put a proper baffled performance muffler on the front to see if that was enought to quell the noise... I too prefer a muffler & resonator set up - they usually deepen the note without it being obtrusive - yet it still flows fine.

If you do get it to work - then make sure to post pics!

[Metako]

I'll try to have a closer look under the car this weekend.

[Metako]

I had a look and it looks like a 3 inch might just fit in there but it is hard to tell until I remove the existing 1 7/8 inch pipe. In the pic the "can" is exactly 3 inches in diameter, so it looks like if a 3 inch wont fit then at least a 2.75 inch (if available) will or two 2.25 inch side by side, which allows the use of a two into one muffler.