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gs stage 1 exhaust system ??


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i have a 1971 GS stage 1 and i am going to the pure stock muscle car drags. i need a 2 1/2 exhaust system that goes from the exhaust manifolds to the N-25 umpers. everyone makes them to attach to headers, but i need them to manifolds. i am looking for exhaust that will pass the judges at the BCA nationals (so it must go from manifolds to mufflers in one piece) and rip it up at the PSMCDR.<P>if anyone can help or if anyone knows people in the philly area to fabricate mandrel bent exhaust i would appreciate it.<P>john grin.gif" border="0

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Riv 73<BR>I can't answer your question, but I was wondering if your car has 2.5 inch outlets on its exhaust manifolds. My non-GS has 2.25 and I figure with non-mandral bends and a 2.5 inch system it works out to about 2.25 on the curves and costs a lot less.<P>Tomsriv<BR>71 Riv

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that is a good question. i have had the exhaust manifolds ported and modified. i think that the 2 1/2 exhaust running from mainfolds to tips will give me a 25-50 hp increase over the 2 1/4. this is one of this "stock appearing" cars that has a modified cam, ported and modified intake (cast iron), modifed Q-jet and increased comp over a regular stage 1. <P>i plan to take it to the Pure stock muscle car drags this sept. i found the guys who have this exhaust system. they are in the buick club mag. i forget their name but i called them yesterday and it was $300. these are mandrel bent and do not have creases or crimps around the curves of the exhust pipes. <P>i think that i am going to get it from them in the summer, and then go kick ass at the PSMCDR!!<P>john

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<B>i think that the 2 1/2 exhaust running from mainfolds to tips will give me a 25-50 hp increase over the 2 1/4. </B><P>I think open tube headers will give you 40 HP if you're lucky. Don't know about the HP gain with your closed exhaust system running through ported exhaust manifolds? frown.gif" border="0 <P><B>this is one of this "stock appearing" cars that has a modified cam, ported and modified intake (cast iron), modifed Q-jet and increased comp over a regular stage 1</B><P><B>i think that i am going to get it from them in the summer, and then go kick ass at the PSMCDR!!</B><P>I take it you're not going to tear down your engine and certify your car as "stock" at the Pure Stock races. grin.gif" border="0

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no i am not going to tear down my car. i have read the rules extensively and you can port your maifolds up to a set limit. also the rules state nothing about the cam and such being stock. they just have to make 16 psi vaccum at 1200 rpm. <P>how many of those cars running sub 13 sec times do you think are bone stock? but this is not a thread about the PSMCD. i am going to have fun. my car was build prior to me wanting to go to the PSMCDs (1996). <P>also i think that the increase to 2 1/2" will give me a gain that is worth the money. <BR>straycat.. the 40 hp gain in open headers is verses the closed exhuast itself. if you compared the headers with 2 1/4 exhaust vs the 2 1/2 exhaust... i think that you will see a nice gain in hp. 50 is pushing it but i defuinately think taht the 25-30 hp is more likely (the fifty was more than likely a pipe dream wink.gif" border="0)<P>also on the tear down stuff... i am going to have fun not prove something. my car runs what it runs. i am just trying to make it conform to he rules.<P>john

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I have 2.5 inch exhaust on my '68 GS 400 Convertible 4-speed, the exhaust was purchased from Torque Technologies in Valdosta, Ga, several years ago with the head pipes. I'm using Dynomax mufflers from JC Whitney, they were $29.95. Been on the car for probably 4 or 5 years, still looks good and sounds great. And I installed it all myself too, and run the PSMCDR too! The head pipes replace where the headers would go, and so you have an extra joint in the system, which I mig welded, so there's another avenue to investigate. Roberta

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