ok i have shorty headers using 2 1/2 304 stainless tubing straight duals with magnaflows that r 2 1/2 pipe with 4 inch OD paking 14 inches long straight threw.. the motor is a 351w.. how is it going to run.. do i need somthing thats not straight threw to give me back pressure???

 

That all sounds about right. Do you have a crossover X or H in the pipe setup?

 

nah its straight 2 pipes.. why is doing they H or w.e make it better .. is it going to run good tho with the straight threw magnaflows.. i hear people saying im not ganna have back pressure and its ganna run like ****

 

?

 

Is your exhaust going over the axle? The pipe will provide plenty of back pressure. A little restriction will increase your low end response.

I run dual 2.25" pipes into open turbo mufflers that dump before the rear axle. Runs great.

 

no be4 the axle and im just dumping them right out to the ground with a little 45 Deg

 

Running a crossover pipe equalizes the exhaust pulses from both banks and helps w/ scavenging, which produces more power. Your setup doesn't sound like it will have much backpressure if your dumping them after straight-thru mufflers.....that will give you more top-end hp, but your low-end tq will most likely be pretty bad.