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Old 11-14-2002, 09:03 PM   #1
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Default Straight PiPE or Cat?

I was wondering what would be more benifitial(at least for HP), a straight pipe from the headers to the muffler, or a high flow cat in place of the stock unit, with a pipe to the muffler?
I have heard about losing the back pressure, but is it the same when you run a straight pipe with no exhaust, and with exhaust? Or does the cat play that much of a role in the backpressure?
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Old 11-14-2002, 09:45 PM   #2
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Well besides the fact that it is highly illegal a modern highflow cat does not flow that much better then a straight pipe. Most modern motors are designed for a little bit of back pressure and won't run well without it.

Here is a backpressure study for you too.

http://www.thrashercharged.com/L67_htm/exhaust.shtm
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Old 11-14-2002, 10:59 PM   #3
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ADTR will offer high flow cats that will bolt up as well as test pipe'* for Bonneville'*. Test pipe will benefit since these engines are meant to breathe and prefer the top end rather than the low end.

-Hector
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Old 11-14-2002, 11:45 PM   #4
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Quote:
Originally Posted by 99BonnevilleSE
ADTR will offer high flow cats that will bolt up as well as test pipe'* for Bonneville'*. Test pipe will benefit since these engines are meant to breathe and prefer the top end rather than the low end.

-Hector
I need these things NOW !
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Old 11-14-2002, 11:46 PM   #5
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I have money!
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Old 11-15-2002, 12:02 AM   #6
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Quote:
Originally Posted by vze3r85p
I have money!

Sounds good. :P I will get rolling on it if people are interested. As for the 95 Bonneville, I talked to Jet and they did not have an answer for me right there. I am going to email their tech support about the 95 since the person I talked to on the phone did not know about the 95 chip option. But for 96 and up, I got this reponse

"For the 96 and later models,We do have a Power Control unit available
for your application. The PCU box would mount under the dash and you would
route the wiring out under the hood. You will have to tap into the TPS
wire and splice the MAP or MAF wire, depending on the application. The
PCU will gain an average of 10-12 hp on most applications. Suggested retail
is $259.95."

Obviously I would get a better price. I am going to see about 95, just e-mail me again.

-Hector
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Old 11-15-2002, 01:14 AM   #7
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I will get back to you tomorrow if Jet has a chip for the 1995 Bonneville'*. I found the email, just have to digh through my 10-20 emails a day that I get.

-Hector
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Old 11-15-2002, 10:47 AM   #8
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Quote:
Originally Posted by 99BonnevilleSE
Quote:
Originally Posted by vze3r85p
I have money!
But for 96 and up, I got this reponse

"For the 96 and later models,We do have a Power Control unit available
for your application. The PCU box would mount under the dash and you would
route the wiring out under the hood. You will have to tap into the TPS
wire and splice the MAP or MAF wire, depending on the application. The
PCU will gain an average of 10-12 hp on most applications. Suggested retail
is $259.95."
This is the same identical response I received 8 months ago. I guess they have a "form" email for this. Do they really have it, or are they just producing a generic module?
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Old 11-15-2002, 01:49 PM   #9
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Well so far all I have done to the exhaust system is a muffler and after reading the exhaust research, it seems that unless I remove the entire system after the cat there will be no great increase in HP. This is ok, I just wanted to know, overall, if I should spend the time and invest in the high flow cat and and get new pipe from the headers to the cat to the muffler? Should I increase the pipe size to 2.5?(I think that is the size now anyway) Or will the out come be almost the same as if I just leave it the same?( I still have everything else stock, but the muffler is a high flow type) ps thanx Azwed for the info
O and illegal doesnt bother me -check out my car if you dont believe me
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