2.5" or 3" pipes for V6?

From: Bob Tom (tigers@bserv.com)
Date: Mon Dec 07 1998 - 07:49:59 EST


>I would like to modify the exhaust system on my 97 V6 Dakota with auto
>transmission. I've heard that the stock system is 2.5" and that it is big
>enough for the 3.9L V6. If this is true, than I should just get a freer
>flowing muffler (less $) instead of a 3 inch cat-back system (more $).
>What opinions are out there on this?
>And do they make headers for this year V6 Dakota????
>Thanks,
>----CONAN

Here are the opinions from three of the pros that I've come across.

Borla says:
As a basic rule, if the vehicle is used for your daily driver and if
it has a fairly stock engine, you'll be happier with a smaller system.
The performance you'd gain with the larger system usually isn't worth
the loss of better sound quality. However, if the engine is very built-up
and if you race it on weekends, you want to reap the benefits of the larger
and louder 3-inch system.

Flowmaster says:
Flowmaster doesn't recomment 3-inch for street use because of the sound
legality side of things. Basically, a 400hp engine is quite happy with
2 1/2-inch exhaust.

Dynomax says:
Bigger isn't always better. Systems that are too large in diameter can
actually hurt performance. To determine which pipe diameter will be best
for your system, decide what rpm range your engine will operate at most
of the time. Small diameter pipes usually produce better low- to mid-rpm
torque. Larger diameter pipes usually produce more mid- to high-rpm torque.

My personal experience (which goes back to the 50's) would say that their
opinions are right on the money. I think there are 3 reasons for wanting
to go with an aftermarket system: performance, sound, appearance. Order
of importance varies naturally with the driver.

Uless your V6 is highly modified, I would not go with a size larger than
the stock pipes. A hi-flow muffler will give you a bit of a performance/
efficency gain and a deeper sound.

Hope this is useful.



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