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Discussion Starter #1
SLP exhaust is 2.5" and Stainless Works exhaust is 3". Which one would be better for our cars?




MSRP for the Stainless Works exhaust is $699.
 

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Difference isn't gonna be that big power wise. The Stainless works exhaust being bigger may give up some ground clearance. Both seem to be great systems. The chambered stainless works exhaust will be the loudest i predict but a loudmouth setup SLP will be pretty close.


All in all i wouldn't worry too much about pipe diameter. Mandrel bent is the biggest requirement. True duals don't require the sewer pipe that fbodies need so basically a true dual 3in system is setup to flow for alot more than the stock motor can throw at it.
 

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Adam4356 said:
Difference isn't gonna be that big power wise. The Stainless works exhaust being bigger may give up some ground clearance. Both seem to be great systems. The chambered stainless works exhaust will be the loudest i predict but a loudmouth setup SLP will be pretty close.


All in all i wouldn't worry too much about pipe diameter. Mandrel bent is the biggest requirement. True duals don't require the sewer pipe that fbodies need so basically a true dual 3in system is setup to flow for alot more than the stock motor can throw at it.
Exactly! I had a 3 in. mandrel bent setup on my 62 BelAir with a 502 big block and could have got by with 2.5 in instead. Would have been alot easier to route on the car, especially around the rear end, where I had air bags in place of the coil springs.
 

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One thing to mention also. If the cars has not seen a lot of modifications (heads,cam,intake) you might notice a loss of low-end torque with the 3 inch pipe. I plan on going to a 2.5 with mild modifications. Just my 2 cents.
 

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Knight Errant
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Exhaust System

I'll be sticking with the stock exhaust for a while, until I can find a set of headers I like to adapt in.

You might find this hard to believe (I know I do) but the Shop Manual, Volume 1, page 6-802 speaks to the system having very low backpressure under normal conditions. This is measured on each side using the J35314-A Exhaust Backpressure Gage connected in place of the AIR check valves or the HO2 sensors locations on each side. The standard at 2,000 RPM is 14kPa or 2 PSIG. I would think that is amazing if not a typo, but it is mentioned over and over in the section. That has to be one of the best flowing full length exhaust systems I have ever heard of, and as they say, if it ain't broke, don't fix it! :thumbs:
 

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Well, and if you notice Old Goat - the vendors selling the aftermarket exhausts don't have any performance gains indicated in most cases. That's because from the people who did post test results, you don't gain anything until you do go to the headers - GM did a pretty good job.
Dan
 

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GTOholic
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I can easily believe our stock exhaust provides very low back pressure. See the "Burbling and Backfires" thread. Some of that noise is cam related, but having a free flowing exhaust helps give our Goats that throaty muscle car sound. I'm looking for headers that bolt into the existing tail pipes and based on what you're saying I don't NEED to buy high flow cats. Cool.
 

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I love Oklahoma. We dont have our vehicle inspections anymore. So, when I get mine, I'm taking it out back and the cats are coming off :D but I may wait for the warranty to expire.
 

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Knight Errant
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Exactly

FLORIT said:
I can easily believe our stock exhaust provides very low back pressure. See the "Burbling and Backfires" thread. Some of that noise is cam related, but having a free flowing exhaust helps give our Goats that throaty muscle car sound. I'm looking for headers that bolt into the existing tail pipes and based on what you're saying I don't NEED to buy high flow cats. Cool.
Exactly what I was thinking when I read that in the Helm's. 2 PSI backpressure normal at 2,000 RPM? Holy Smokes! We might be looking for good shorties but paying attention to length as a divider of 32 or 34. Anyone know what length these motors 'like'?
 

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Knight Errant
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The headers are what is going to provide any gain here like Dan and Florit said. Until you do that, and see what you might (or might not) need after doing them, it is possible one could waste money on an aftermarket exhaust or catback system, unless there were other reasons for doing it (nice 3 inch dual polished stainless on a show car for instance). A certain amount of backpressure is necessary in an exhaust system. I do not believe the engineers would have dipped below the minimum. It is now easy to see another reason they were so proud of this exhaust system.
 

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If you aren't planning a major power adder, then the 2.5" system is MORE than sufficient. If you're planning on heads & cam, stroker, supercharger, turbo charging and Nitrous on top of any of these, I'd go with the 3" system.

The bigger you go, the more HP you'll get as the engine is able to rev freer, but due to loss of backpressure, you'll sacrafice some torque.
 

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???????

I have about 375hp at the ground, and i plan on camming it and super charging it. but i dont want a loss of torque in the mean time so should i wait to put the three inch on??? or do i have enough horse power to get away with it??
 

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May I quote you on that?
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We have a necrophiliac of the year nominee.
 

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So it goes.
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Oh wow. This is the oldest thread I've ever seen.
 
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