I want to have my exhaust end before the rear axle under the car; I like the hidden look since taking off my muffler. Has anyone successfully pulled this off on a thirdgen? I'd like to have a high-flow cat and something that will quiet it down as much as possible in what little space there is under the car. Any suggestions?

 

No matter what muffler(s) you use, exiting under the car is going to be louder with regard to interior noise than exiting outside the car.

Most states require the exhaust to exit beyond the passenger compartment. With a hatchback, it could be argued that dumps in front of the axle do not meet that requirement.

My suggestion would be to take it over the axle, then get it routed beyond the sheetmetal in some fashion or another.

 

Interesting bit of info... I imagine it's to keep exhaust fumes from entering the passenger compartment. Interior noise isn't a concern for me.

Let's say I can get around this and still get passing emissions (given good exhaust numbers). Are there certain types or brands of mufflers that work best for this application? I understand that it will be louder than the stock routing, but right now I'm driving without a muffler at all and anything would be better than this.

 

i'm using moroso spiralflow mufflers on my true dual exhaust that ends before the axle.

 

I suggest you stop dreaming
I'm going to have to say there's slim to no chance of both happening. Either one (the muffler) or the other (cat.) is going to eat up the space there and not leave room for the other.
If you choose a bullet or glasspak then you're giving up quiet. No cat., emissions.
I ran for a few weeks with my exhaust chopped off at the rear (changed fuel pump) before I finally got sick from fumes (literally, stoplight, exhaust, windows down, no wind..) and the obnoxious interior noise.
I've got one of the old mufflers from my 'bird (14" case length) on my camaro, it's not loud (as it's on a stock lo3) but, the closer the end of the pipe get to the driveres seat, the more (morning especially) commuting starts to suck....

 

on my towncar i backed up too far crushing my exhaust over the axle. cut it off. then my muffler broke its weld that held it in place and it bent around the axle crushing it. cut it off. then my passenger side manifold decided to drop the pipe 1/2 inch.

the stock 4 cats quiet it but its still loud. and ***tty

 

This may work if you add a cat before the muffler

 

your just screwed Next winter if I dont tub it, I'm at least cutting out the rear floorboard so I can put the mufflers someplace. Redid with 3" pipes and made a new crossmember for the TH400 and literally the only thing you can see from a side profile is the mufflers. Lots better than my old set-up that a shop did. Only pic I have on file right now. Very loud inside car, sets off alarms when driving in a parking lot.

 

I would suggest against doing the mufflers before the axle.

 

This is pretty much what I was thinking. The Y looks like it could be moved forward and then put the cat where the Y is now.

I imagine that's pretty loud.

 

IHI, don't tub your car man! i love stock style suspension cars...

 

It's working great now, but I've always loved that Pro-Strret look

Current combo I kinda shot myself in the foot. Told Bullet I was leaving on a trans brake and did'nt wanna over power a 10" tire, so my 60' is pitifull. But on the lighter side the hp pulling on the big end is VERY consistent!! "shoulda" wen twith a 108-110 lobe serperation, but at least with this I can run my future nitrious with no troubles Slowest wheel pulling car a person can witness right now, lol!!

 

look at the drag radial guys running mid 8's spraying off the line with a trans brake...those guys hook just fine! if you can man, i would say leave the car the way it is...

 

I'm utterly confused as to why you'd want to have SINGLE exhaust dump underneath the car like that. Do you have any idea how loud it will be inside and out? You may think its "cool" for the first few weeks but when you rattle your teeth out you'll be saying "boy, I have this annoyingly loud car with half-assed exhaust, my neighbors think I'm an idiot because I set their alarm off every day and the guys with fast cars laugh at me because I make all this bark but cant back it up because all I have is a stock 305"

Get a dynomax or hooker catback, throw away the tailpipes and then have someone custom make you tailpipes that tuck up underneath the bumper. Now you have a full exhaust system with a "hidden" look thats quiet.

 

LOL... no need to get upset man, I'm just looking at options. Personally, I've liked this setup since I saw and heard it on a (gasp) 5.0 GT a few years ago. Of course I will need a a good engine, but getting the exhaust done is my first concern at the moment because I have none! I figured this would be an interesting setup that few have done and wouldn't be nearly as loud as it is now.

With a new engine comes a new exhaust, which means I'll be changing it again in the future.

 

My car is very quiet with the cut off dynomaxx super turbo mufflers right before the axle BUT my ground clearance is suffering now so I am thinking about shortie headers with a single 3" pipe into a hooker cat back..

 

Here's mine:

 

I still have lots 'O' ground clearance too

 

last one.

And because the tips exit the sides, there really isn't any reverberation in the interior. And they're still hidden unless you're on your knees

They're edelbrock stainless muffs. Only about 3.75" thich IIRC.

 

That's a pretty nice design, onebinky. Only problem for me though is I have perimeter SFCs installed, and I don't think the exhaust would fit there. Glad to hear it's not too loud.

 

That's gonna be an issue for me too, I almost wish I would have waited to do the exhaust until we made up the SFC's. Could probably get away with less bends on them that way. Oh well, I'll worry about that when the time comes

 

So long as your like me and really **** about the cars tune (ie stock wise it can be a tad rich) the exaust is almost odorless. Doesnt smell at all in the interior. I jsut get a bit sleepy if its been idling in one place to long...

No, actually the exaust velocities from small 2.25 in. outlet are so high that it actually sets up a flow of air that carries the exaust out past the rear drivers side tire, which also seems to suffer from accelerated dry-rot. Hmmm, I wonder why? As for the noise level, Ive never been able to hear much of it since I cant hear very low frequencies although other people outside the car complain about the noise level as soon as I get within a mile of them so I can only imagine it must be very obnoxious in the interior. On a positive note, mounting a blowmaster muffler off the y-pipe is the only application in which it doesnt rot out internally after a weeks worth of use. I think thats normally termed 'breaking in'.

 

That's because CO is odorless.

 

I know... I guess I forgot to insert the humor in my first statement. What I have there is a temperary solution thats been a bit more perminent then it should. Its not bad like my S-10, though. The entire exaust fell off one day and later after I got home, I became violently ill from CO poisoning. Never used it again like that, thats for sure.

 

Ouch...

The same thing happened on my ranger, I've been driving it like that for a few months now until I find the time to fit up a new exhaust. Haven't gotten sick yet, but I've gotten a few pretty nice headaches from the CO.

 

How loud is it ?, and how is the ground clearence? That is the setup that I was considering going with. Got any pix?

 

The law is [least around here[ the exhaust can exit out in front of the axle but that is as far forward as it can go. its a safety hazard as it to easy for fumes to find their way inside the car.

So You could have the mufflers stop right at the axle. 2nd gen guys do that allot.

But a muffler never sound right unless it has some sort of tail pipe. Don't know why but the sound is much cleaner with just a tad bit of tail pipe.

Of course I just have a single so it was 1000 times easier but I was done with the fake dual out the back look and ran a straight shot single out the left side.


I do like the one a few up. Its ends early but has tips to direct the sound out form under the car. Along with the fumes.

 

Though I do wonder about the ones ran near and close to the frame rails / edges of the car. There are fuel lines and return lines near there and you could be heating up the fuel. Id kept it that way but maybe put some insulation between the pipe and fuel lines. Course that may only matter to the serious drag racer when a few degrees lower in fuel temp means a tenth or two.

I think the return runs down the right side? Most GM cars are done like that.

 

i have true duals with an x-pipe and bullet race mufflers dumped before the rear axle. i have no problems with ground clearence issues. only problem with the way mine is ran, is that whenever tranny work or any work in that area has to be done, the entire exhaust has to be dropped.

you could do it like i did or like some of the other guys that have posted did....or you can get a new y-pipe with no cats and just stick a dynomax bullet, moroso spiralflow, spintech, or another muffer of the same style directly on the y-pipe and be done with it. only problem with doing it this way, is that it is extremely loud as the muffler is right under the front floorboard.