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Discussion Starter #1
has anyone replaced just the front resonator and pipes only and leave the pre-muffler when you did a muffler install?

If so, did the system get much louder? Did you lose any bottom end torque?

I have the Comptech mufflers and last weekend I was having the Comptech tips installed and the Muffler tech noticed the most restrictive pipe (smallest diameter) is between the front resonator and the back pre-muffler, approx. 1 3/4 pipe. I replaced that one pipe only with a 2 1/2 pipe which is approx. the size of the pipes before and then after this section of pipe and resonator. Also the pipes are strangely bent for what we believe is resonance suppression.

Seems to rev up quicker now with only a slightly louder resonance. I considering removing the front resonator and stock pipe and running one long straight 2 1/2 pipe to the back pre-muffler. This should improve flow but I'm concerned about losing bottom end torque and louder resonance, especially because I will be removing the resonator which is right below the drivers seat and the resonance may get really loud, I don't mind the sound of a nice loud snarling exhaust but I cant stand that annoying resonance!

Thanks in advance for your help.

Brad
 

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apologies in advance for not really having an answer to your question, but i wanted to point out what seems to me like a flaw in the reasoning behind getting larger pipes. im sur eyou already know why backpressure is needed, but also dont forget that while having large diameter pipes will give u more freedom at the high end, for anything else you need to maintain a substantial flow velocity in your exhuast. if u open up the pipes too wide, the pressure drops, and subsequently flow velocity drops. the reason why im pointing this out is bc i think that your 2.5" pipe is too large.. i would think 2" or 2.25" tops would be an appropriate diam, unless youre gearing up for FI ;D just my $.02 hope it was helpful!
 

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Discussion Starter #3
sumptimwong said:
apologies in advance for not really having an answer to your question, but i wanted to point out what seems to me like a flaw in the reasoning behind getting larger pipes. im sur eyou already know why backpressure is needed, but also dont forget that while having large diameter pipes will give u more freedom at the high end, for anything else you need to maintain a substantial flow velocity in your exhuast. if u open up the pipes too wide, the pressure drops, and subsequently flow velocity drops. the reason why im pointing this out is bc i think that your 2.5" pipe is too large.. i would think 2" or 2.25" tops would be an appropriate diam, unless youre gearing up for FI ;D just my $.02 hope it was helpful!

You are right - I was approximating the pipe size, I believe the pipe I installed is no larger then 2 1/4 inch. I'm trying to copy existing cat-backs and I believe the Comptech's is 2 1/2 and so is the Greddy - so you have hit the nail on the head - what can we open up or system to, to get both top end HP and bottom end torque?
 

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a general rule is to open up stock piping 0.25" unless you plan to go FI in the near future. im not familiar with the exhaust setup on the v6 bc i own a L4. but as far as the catbacks and mufflers on the market.. most of them open it up wide so they can advertise their WOT whp gains. most buyers are too ignorant to consider other specs.
 

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sumptimwong said:
a general rule is to open up stock piping 0.25" unless you plan to go FI in the near future. im not familiar with the exhaust setup on the v6 bc i own a L4. but as far as the catbacks and mufflers on the market.. most of them open it up wide so they can advertise their WOT whp gains. most buyers are too ignorant to consider other specs.

Comptech says it uses 2 1/2 inch pipe:

http://www.comptechusa.com/store/product135.html

Like you said, the gains don't really start until 5k rpm:

http://www.comptechusa.com/images/dyno/accordv6catbackDyno.pdf
 
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