Too much exhaust flow = loss of power

codyGT said:

You would think it is common knowledge:

Less backpressure = Less low end very little more top end
Normal back pressure = Good low/high end

More backpressure doesn't = More torque
No backpressure doesn't = More high end

It's all about balance.

Dual 2.25 pipes is more than enough for a N/A 4.6 under 400hp.

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He's absolutely right.

I run 2-1/4" , all four cats, plain old H crossover, and turndowns right on the mufflers. ALL done for best torque. It's a street car and would-be road racer. It really likes ANY extra bottom end it can get for coming off those slow corners.

A chambered muffler does not slow the gas velocity through the 'system', only through the mufflers themselves. Trust me, I know this to be true. That's one reason 'chambered' mufflers get that sound.

thanks indiana