Free Flow Exhaust

NY90RedSC

Registered User
What company manufactures the free flow exhaust for the 89-93 SC? The 90 SC we're getting has blown head gasket syndrome and I would like to add the free flow exhaust to help reduce the backpressure on the engine to avoid any further problems in the future. Any help is appreciated.
 
Flowmaster makes a two piece kit for the 89-93 and the 94-95. The 94-95 design is better as it goes straight to the back instead of around the tank like the 89-93. Swap in a gas tank from a later year and get better flow.

SCP also sells a couple of other versions depending on flow requirements. Flowmaster claims their setup is good to 500 hp.
 
its actually the 92 and up tbirds that had the better exhaust routing.

i dont believe flowmaster's setup is good for 500hp.

the whole kit uses stock size piping. 2" downtubes, 2.5" around the tank and 2.25" from the axle back. the only things it replaces is the resonator and the mufflers.

if i had to guess i'd think it'd be good for 300 hp.

now the SCP exhaust is 2.5" downtubes, 3" around the tank and 2.5" from the axle back. much better for flow.

you can probably get your local exhaust shop to do it for a bit less than SCP's price.
 
i thought the stock downtubes were only 1 7/8" 's??? not to mention the stock isnt mandral bent.
 
i thought the stock downtubes were only 1 7/8" 's??? not to mention the stock isnt mandral bent.

ok sorry 1 7/8". but trust me, that 1/8 increase in the downpipes is not a big improvement. and its after the cats anyway.

i think the stock exhaust would flow well if not for the downpipe angles and the crap resonator.
 
its actually the 92 and up tbirds that had the better exhaust routing.

i dont believe flowmaster's setup is good for 500hp.

the whole kit uses stock size piping. 2" downtubes, 2.5" around the tank and 2.25" from the axle back. the only things it replaces is the resonator and the mufflers.

if i had to guess i'd think it'd be good for 300 hp.

now the SCP exhaust is 2.5" downtubes, 3" around the tank and 2.5" from the axle back. much better for flow.

you can probably get your local exhaust shop to do it for a bit less than SCP's price.

The kit that was on my car when I bought it, 4 years ago, was the flowmaster setup, without cats.

Now Im pushing over 300 horse, and over 400 torque.

But Im not saying this is the best setup, as I am too, looking to upgrade from this setup.
 
I'm running 3.27s in my 5spd and it is right in the sweet spot of my HP\Torque in fourth gear at highway speeds. This makes for easy passing and getting away from ignorant drivers.
In 5th at 70 mph I turn about 2800 rpm which makes for pretty good gas mileage and not a strain on the motor.

Also in 3rd gear around town speeds (35-45 mph) it has the same range to really get the most HP\Torque from my almost stock motor.

I think it's the best gear going for normal usage in most street conditions.
 
The Flowmaster kit actually consists of 2.25" pipes into the resonator, 3" to the splitter and then back to 2.25". Flowmaster does not supply downtubes. All pipe is mandrel bent which affords 30% increase over same size non mandrel pipe. So the tiny 1 7/8" stock pipes will not even come close. The angle at the cats is brutal and is a major stumbling block to flow.

They suggest running 2.5" (if headers support) downpipes reduced to 2.25" into the resonator. They had some new single pipe resonators capable of flowing more so I called the tech line to discuss this as an alternate route. They tech told me they had the force II system on an SC coming close to 500 hp with no issues and that the M90 style superchargers were too small to max out their setup.

We put this system on my bro's 93 along with ceramic coated Mustang headers. Prior to coating, I blended all the welds and removed any flash from the inlets. The collector was opened up to approximately 2.5" from the factory just under 2.25". The brutal welds inside where the pipes met were also ported to a nice smooth transition. I had two downpipes made at a local shop and the gradual bend left almost no kink in the pipes. Cats were deleted. The car had a piggy back chip, underdrives, 10% overdrive sc pulley already. Performance improvement was substanial.
 
its actually the 92 and up tbirds that had the better exhaust routing.

i dont believe flowmaster's setup is good for 500hp.

the whole kit uses stock size piping. 2" downtubes, 2.5" around the tank and 2.25" from the axle back. the only things it replaces is the resonator and the mufflers.

if i had to guess i'd think it'd be good for 300 hp.

now the SCP exhaust is 2.5" downtubes, 3" around the tank and 2.5" from the axle back. much better for flow.

you can probably get your local exhaust shop to do it for a bit less than SCP's price.


Im not sure even that on SCP.com it says it becomes a restriction on cars 250-275hp. Im not sure if were talkin about the same system tho
 
I appreciate all the feedback on this setup guys. Obviously I would like to get the most flow for the buck, but I'm also not looking to push 500hp with my SC. I am very happy with the stock performance of the SC and am more concerned with doing all I can to relieve the stress on the head gaskets to avoid a future failure. Flowmaster looks like a decent setup, but the SC Peformance system also looks like it will do a fairly good job of exiting my exhaust gasses without restricting the flow like it is now with the stock setup.
Also, what seem to be the most popular headers for our 3.8's? If I'm going to upgrade the exhaust, I might a well do it right from the manifolds back by swapping in a good, efficient set of headers.
 
unless you're making huge hp numbers, just port your stock manifolds.

i think a good system for cheap would be catless downtubes and a better resonator ( borla, magnaflow, flowmaster). and everything else keep the same.

of course its not a good setup for 300+hp but for stock or mildly modified its plenty
 
from what i've read,get the 94 pasg. side exhaust manifold and than port the collector on both manifolds.
 
Magnaflow (or Carsound) makes downpipes for 89-93 and 94-95 cars with 2" mandrel-bent pipe and catalytic converters. I bought a set and they look really nice. They make a much smoother transition from the manifold to the cats than the stock pipes do. I have not yet installed them, so I don't know how well they work.

However, I have heard that some people found the quality of the cats to be substandard. Someone here said their Carsound cats plugged and blew a head gasket. Definitely something to watch out for.
 
Magnaflow (or Carsound) makes downpipes for 89-93 and 94-95 cars with 2" mandrel-bent pipe and catalytic converters. I bought a set and they look really nice. They make a much smoother transition from the manifold to the cats than the stock pipes do. I have not yet installed them, so I don't know how well they work.

However, I have heard that some people found the quality of the cats to be substandard. Someone here said their Carsound cats plugged and blew a head gasket. Definitely something to watch out for.

Are they stainless or aluminized piping? Where did you get them?
Mike
 
So, reading all this, would one be good to replace the resonator and mufflers, and leave it at that? I'd like a little sound from my car, and the resonator is the worst spot for restriction. If I could just find a muffler similar in size to the stock unit that flowed better, and used the Magnaflow resonator, would I achieve my goals?
 
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from what i've read,get the 94 pasg. side exhaust manifold and than port the collector on both manifolds.

I did this on my 89 titanium automatic car when I did the H/G swap, and it worked well. I spent about 45 min/manifold grinding out the "ring" on the I.D. at the collector end. I read that's all that's needed; this set up flows about as good as headers for modest street engines according to XR7 Dave.

The 94 manifold has a different outlet location, so it will require a different down tube. A good opportunity to delete the cats...

JD
 
So, reading all this, would one be good to replace the resonator and mufflers, and leave it at that? I'd like a little sound from my car, and the resonator is the worst spot for restriction. If I could just find a muffler similar in size to the stock unit that flowed better, and used the Magnaflow resonator, would I achieve my goals?

if you're not planning on doing alot of upgrades, just a few bolt ons, then replacing those things would be good.

maybe even think about getting some custom downtubes, with or without cats.
 
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