exhaust 'note'...?

K

Kit Sullivan

Registered User
On my stock 90 SC, if I replace the stock down tubes/cats with 2 1/2" tubes with no cats, and remove the muffler completely, leaving the rest of the exhuast and resonators as is, will that help the performance? And will it have a good sound. I'm not looking for a raspy, popping sound, just a deep mellow tone.
Thanks to all.
 
It will sound horrible. When I bought my 95 it was sporting deleted cats and mufflers and the noises it made were unbareable.
Ehdrian is right about the resonator being one of the most restrictive parts.
 
OK, so how about maybe a pair of glass-packs or something in place of the big muffler in the middle, and just doing away with the resonators altogether?
 
The big muffler in the middle is the resonator. If you get rid of the cats and rear mufflers your car will sound terrible. No way around it.
Your best option if you are dead set on getting rid of the cats and want to keep it cheap is to replace your cats and resonator with a Magnaflow resonator and custom downtubes connected to the stock rear setup.
If you want to spend some money...The full Flowmaster exhaust kit for the SC with custom downtubes sounds pretty good and is a lot better than the stock stuff.
 
You can get 21/4" down tubes from Wynne (Texas Thunderbirds) you dont dont need 21/2" That is overkill unless you plan on 400 rwhp or more. Get a dual 21/4" in 3" out resonator. Run 3" all the way back and split to two 21/4 pipes.Get some after market mufflers and you have a fairly nice sounding exhaust. If you take short cuts like loosing the resonator you will hate the droning sound your exhaust makes. Keep it simple but dont short change the exhaust system

Ken
 
It looks like Summit racing sells the Flowmaster 'Force II' cat-back system for $270, including 40-series delta-flow muffs.
The resonator is another $130, but it is unclear if this is any improvemnt over the stock piece. Flowmaster lists the resonator as having 2.0" inlets and a single 2.5" outlet, whereas Summit lists the same part as having 2" inlets and outlets. Anyone know the story here?

With this kit and no other mods, would 2.25" down tubes w/o cats be appropriate?
 
Kit Sullivan said:
It looks like Summit racing sells the Flowmaster 'Force II' cat-back system for $270, including 40-series delta-flow muffs.
The resonator is another $130, but it is unclear if this is any improvemnt over the stock piece. Flowmaster lists the resonator as having 2.0" inlets and a single 2.5" outlet, whereas Summit lists the same part as having 2" inlets and outlets. Anyone know the story here?

With this kit and no other mods, would 2.25" down tubes w/o cats be appropriate?
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Their system is most likely closer to stock size to make installation easier. I am sure that it would flow better than stock but cant say for sure. Wynne moved his shop from where he was and appearantly hard to get ahold of. Try sending him a PM. I bought a set of his 21/4 down tubes before, much better than stock. My suggestion was based on what a lot of members here have done. I originall went with with the system I recommended to you. I since have installed headers and mandrel bent 21/2" downtubes since I am aiming at a fairly high level of power.

Ken
 
What size is the factory-installed mid-pipe? (the one betwwn the resonator and where it splits for the mufflers). The one on mine looks huge...maybe 3" or so. Is that stock?
 
Kit Sullivan said:
What size is the factory-installed mid-pipe? (the one betwwn the resonator and where it splits for the mufflers). The one on mine looks huge...maybe 3" or so. Is that stock?
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I dont know for sure if it was 2, 21/4 or 21/2 but I know for certaint it wasnt 3". I just wacked mine off behind the resonator and behind the pumpkin, took it to a muffler shop and asked them to reproduce it in 3". Cost me 50 bucks at the time

Ken
 
kenewagner said:
You can get 21/4" down tubes from Wynne (Texas Thunderbirds) you dont dont need 21/2" That is overkill unless you plan on 400 rwhp or more. Get a dual 21/4" in 3" out resonator. Run 3" all the way back and split to two 21/4 pipes.Get some after market mufflers and you have a fairly nice sounding exhaust. If you take short cuts like loosing the resonator you will hate the droning sound your exhaust makes. Keep it simple but dont short change the exhaust system

Ken
Click to expand...

It might be quicker to get them from SCP as Wynn seems to be unreachable the past 2 months. Also, if you really look at the stock resonator it's a real piece of work. two pices hooked together by a single section of pipe.. it's awful.
 
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On my 92 SC I have the Force II kit and flowmaster resonator.

The stock cats have been removed and I had new downtubes made, but they are only 2.0". The flowmaster resonator will fit over the stock 2" pipes and clamp on. Then it has a single 2.5" outlet pipe and y's into 2 1/4" in the rear with 2 mufflers.

I have a 90 SC here that is a project car. It has stock cats still and a flowmaster resonator. It had the flowmaster mufflers when my friend bought it but he had them removed and straight pipes in place of them. It has the rear bumper cut out and the pipes poke through. It was pretty loud when it ran but not too unbearable, plus in the car it was fine since the sound went out the back.

On my daily driver 90 SC auto I have catless 2" downtubes, stock resonator, and straight pipes out back no mufflers. It sounds decent, not as deep or low as my 92 w/ flowmasters but it sounds louder and more noticeable than stock. Tony says this setup sounds horrible. I don't think he's heard my car but it may be similar to his 95 when he got it. I don't mind it on my car, but I wish it had a lower tone to it. It's not high or ricey, but you can tell it's a 6 cylinder. My main concern is the stock resonator still on it and it's restrictiveness. I am going to just put a flowmaster resonator on it for now, and then have an exhaust shop bend up a 2.5" pipe around the tank and y it into 2 1/4" pipes out the back. No mufflers. This car is all about cheap speed. Mufflers add weight and don't add power, so in the Micahdogg fashion of weight savings, the mufflers are gone. I expect it to get louder with the flowmaster resonator and unless it's too loud I'm not going to put mufflers on it.
 
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Kit Sullivan said:
OK, so how about maybe a pair of glass-packs or something in place of the big muffler in the middle, and just doing away with the resonators altogether?
Click to expand...

Glass packs will work fine. My first custom exhaust had nothing more than two 12 inch glass packs just down from where the cats were....then two cheap turbo mufflers at the very end. It sounded just slightly throatier than stock and no annoying drone in the mid-rpm range. So you don't need a resonator...but you need SOMETHING in the mid section.

Micah
 
I just had mine done last week.....left the factory cats and put a Magnaflow resonator with 3 inch pipe just past the rear axles then split to 2 1/2 out the back with no mufflers. I strongly recommend NOT doing it this way....it sounds horrible! I will be adding two mufflers of some sort to the rear. I was extremely happy with the performance i gained and the fact the motor runs alot cooler but the sound sux.
 
I went with no cat and turbo mufflers, sounds like crap in the mid ranges. I wouldn't reccomend it. Luckly I'm changing out my entire exhaust soon!
 
On my 89SC i had 2 1/2" cats going to a 2 1/4" in 2 1/2" out dynomax res, straight pipe 2 1/2 no muffs...a little drone at 2200 or so...but not bad.
 
I have Wynn's catless downtubes going to the Flowmaster resonator and Force II catback (2 1/2 to 2- 2 1/4 flowmaster mufflers). It sounds almost like a V-8 at idle. It drones while cruising. It sounds raspy at high RPMs. It sounded a lot nicer before I got rid of the cats.
 
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