I am almost finished rebuilding my 2.5 i gernaded the original 2.5 that was in it after a failed rebuild. here is the thread https://www.fiero.nl/forum/Forum2/HTML/091836.html so i was thinking of redoing the exhaust and im not sure what muffler to go with and should i stay with the same size or go up to a 2.5 in or 3 in? i think i have 2in now but not sure haven't really looked into it.

Im not even sure what is a good muffler for a 4 cyl, i was thinking of a cherry bomb http://www.cherrybomb.com/products/extreme i was also thinking of getting the center dual or should i get the center center? meaning dual exhaust or single.

or if someone knows a better muffler and pipe size please post here and let me know what u have and how it sounds.

Thanks
Steven

It doesn't really matter. The Duke won't sound that much better no matter which muffler you choose.

well im not looking for something to make it sound like a v8 or anything just a good sound and not a ricer like most kids about 16 like to make there honda's sound. just something that sounds good at high and low rpm's.

haha i like how your in the exact same place im at :P
do you have a have to keep the cat on for smog where you live? where i live i dont have emissions. so i took the cat off. but i was looking at it. it be a great place to put the red glass pack cherry bomb muffler there. and remove the muffler and you can just get a Y at the rear so you can split it into duel exhaust. thats what im planning on doing. there very cheap mufflers.

My '67 Pontiac LeMans with a 389cid (6.5 litre) V8 breathes quite well with a dual set of 2.5 inch mandrel bent pipes. I would think that if you would be fine with 2 inch or 2.5 inch if you decided to go aftermarket.

Again, the research done on the LeMans brought up this site:
http://www.pontiacstreetper...com/psp/exhaust.html
They went with a Walker #17749 Dynomax to turn their drag car into a sleeper. Depending on what exhaust note you want, this may work well for a quiet ride with good flow.

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Kendall (Icelander) Whitlatch
'85 Fiero 2M4 - 5spd Isuzu
'67 LeMans/GTO clone 6.5 litre TH400
All the rest aren't Pontiacs, so what does it matter?

The Duke tends to sound like an oversized chain saw no matter what kinds of exhaust/head/flow stuff you do to it; I was shocked how similar a 200HP SD sounds compared to my 206k-mile stocker engine.
I ended up going stock piping, cat delete with a straight pipe, and a 14" Magnaflow Ultra-flo welded in place of the stock muffler. Sounds just a tad louder than the stock muffler, but I've got more pull in the 2500-3500 range. I'm going to fab up an alternate exhaust that gets rid of that big 180-bend in the downpipe and just drops straight down and dumps out of the right side through a Cherry Bomb resonator--see if that nets me any gains (and it'll occupy me for an afternoon, either way).

thats a good idea. thats a pretty useless 180 bend if you got rid of your CAT.
i got some 2 1/4 exhaust pipe that is about 3 feet long. i like that idea you have,

quote Originally posted by 3057: The Duke tends to sound like an oversized chain saw no matter what kinds of exhaust/head/flow stuff you do to it; I was shocked how similar a 200HP SD sounds compared to my 206k-mile stocker engine. I ended up going stock piping, cat delete with a straight pipe, and a 14" Magnaflow Ultra-flo welded in place of the stock muffler. Sounds just a tad louder than the stock muffler, but I've got more pull in the 2500-3500 range. I'm going to fab up an alternate exhaust that gets rid of that big 180-bend in the downpipe and just drops straight down and dumps out of the right side through a Cherry Bomb resonator--see if that nets me any gains (and it'll occupy me for an afternoon, either way).

Well let me know how it sounds and if u get any head turns. if it works out good i just might do that my self. i was thinking of have it drop straight down and then bend to the right. but i dont have a welder but i have access to one. but i was just gonna drop it and then have it follow its normal route and put an after market muffler in place of the stock one and i would like to have dual tips. will the dual tips increase or decrease performance?

i believe you will still have the same flow of exhaust. if the whole exhaust is 2" piping it should stay the same. just depends on the higher flowing muffler. and or if you get bigger piping you could see alittle more power. i mostly work on bigger engines. so im not to sure if they comply with the 4clys im not a huge fan of the 4cly but there great on gas so i cant complain to much

ok thanks josh, i might step up to the 2.25 and see what happens or i might get a v6 ocelot and see how that works. i read somewhere that it sounds better with that exhaust than the 4 cyl system.

quote Originally posted by My84: or i might get a v6 ocelot and see how that works. i read somewhere that it sounds better with that exhaust than the 4 cyl system.

I have the factory dual exhaust on my Indy (4 cylinder) and it sounds deeper at Idle and decent enough, but when you get on it, it's just kind of buzzy and annoying.

I have never really heard a 4 cylinder sound anything other than buzzy and annoying at speed, but maybe that's just me.

How much exhaust piping is needed to run a new exhaust? I am looking at running a straight pipe and deleting the cat, then bringing it into a Dynomax 17217 muffler and out to dual tips...All 2.5" piping... And does the duke have a flex pipe off the manifold?

2.5" maybe over kill for the duke.... Just a thought.

And no... the exhaust is all solid metal tubing, no flex joints.

[This message has been edited by jaskispyder (edited 06-20-2008).]

Isn't the stock exhaust 2"? Only reason I am looking at 2.5" is to keep things uniform with the inlet/outlet of the dynomax muffler...

so i had a thought of how to route the exhaust. come off the header straight into a muffler with dual and have is split out to the right and left of the car and dump out just infront of the tires. i got the idea from a newer mustang i saw with dual that dumped out just in front of the rear tires. any one think this is a good idea or or have thought please let me know. there is a spot infront of the rear tires that has a potential of being the spot that im gonna route it too. when i have a chance im gonna take pictures so u can see what im talking about and i might edit them to give a kind of view to how it will look.

I was looking at the extreme too. I like the idea of dumping out in front of the tires. It might be even better when I do the swap. SHOW LOTS OF PHOTOS!

well here is a rough paint drawing of what it will kinda look like. im on a laptop so its not as good as if i was on a desktop.



Remember i am working with a 4 cylinder so i dont know what kind of room is there for a 6 cylinder. If i had one here to look at i would try and see what i could come up with. i have a thought but not sure how or if it would fit. ill explane and try to draw one up.

cam someone email me pictures from under the car between the engine and cab of a v6 and if there is any room to see from up top and how the y pipe connects to the rest of the exhaust system. once i get a mental 3D image in my head i might be able to come up with an idea.

Thanks Steven

I've had experience with both single and dual exhaust on the duke. I'll give you a little rundown of both my setups.

Dual) Pipe was routed exactly the same as stock, from the manifold to where the old muffler used to be. In place of the old muffler I had a Vortex Classic series 2.5 in dual 2.5 outs which led to the tips at either side of the car. I learned the hard way that a) all of the pipes after you split the exhaust, which in my case was in the muffler, must be exactly the same length, or most of the exhaust will just flow out the one side. Which looks stupid. b) I also learned that a large Vortex Classic series muffler will not fit in that little space between the trunk wall and the cradle frame. c) finally, because of the diameter of the 2.5 pipe, I had a hard time clearing the frame to get the pipe to come out to the back of the car at a good angle. So when you looked at the exhaust from the back of the car, one tip was pointing too much outward and one was pointing too much inward. It seriously looked like I had spent about 20 mins hooking it all up. But the car did sound pretty cool, it had a very throaty grumble under acceleration and kind of a chug at idle.


Single) I actually just completed the installation of this a few days ago. I am very pleased with my new single outlet setup. I basically just cut out the old clogged up catalytic converter I had and put in a straight pipe. Then replaced my dual outlet muffler with one of the Cherry Bomb Turbo mufflers with single outlet. I left the pipes all the same so I could just basically cut and swap. The Cherry Bomb is much shorter than my Vortex Classic, so I had no problem fitting it in there and its staggered outlet setup gave me plenty of clearance with my outlet pipe. The car is much quieter now. Its a little bit louder than stock and has a nice sound under acceleration. The sound is a nice balance between fart-can ricer and muscle car.

All in all its entirely your decision. From the look of your drawing you may have a tough time finding a safe place to put a muffler like your describing. Really the only place in the engine bay you could fit any kind of muffler is between the engine and the firewall or the engine and the trunk, otherwise your putting the muffler at risk of being ripped off by anything that should pass under the middle of your car.

I had an 87 coupe that had a formula bumper on the back and a transplanted GT exhaust. It sounded nicer than my all-stock 85 single exhaust. Nicer, not awesome.

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John DuRette
Custom 85 SE/86 GT
"Kinda makes you nostalgic for a Members Only jacket"

I wouldn't think theres enough room to put the exhaust out the side, the car is too low, might scrape it. A pipe that short will be really loud especially without a muffler, glasspacks really don't muffle much. you'd for sure get attention if thats what you are going for.

quote Originally posted by 2.5: I wouldn't think theres enough room to put the exhaust out the side, the car is too low, might scrape it. A pipe that short will be really loud especially without a muffler, glasspacks really don't muffle much. you'd for sure get attention if thats what you are going for.

There is a section in the skirting that is just empty i was thinking of cutting a hole or replacing the skirt and making a new one to accommodate the exhaust so it would then be at the same level as the bottom of the car. if you look and feel just in front of the tire in the skirting you will see what im talking about. the only concern i have is that it will be close to the coolant line and im sure it will make the coolant hotter. unless i insulate both the coolant line and exhaust pipe in that region.

Steven

OH ya, that could work, and a wrap for the coolant tube is probably enough if it doesn't touch the pipe.