what is it exactly i heard mustangs have to have it or something...i dont know help me out

 

Backpressure is literally when the exhaust gases are choked up in the exhaust, and cause a resistive pressure.

Think about it....the hwole goal of building a motor is to make it more effecient and let it breath. How will choking the motor help at all?

It is bad. Anything and anyone saying it is needed is subscribing to the idiocy theory.

What is a much better idea is to minimize the backpressure, while maximizing the exhaust velocity, which will aid in scavanging a lot.

 

Back pressure refers to the pressure that actually the gasses that come out of your engine have. For example if your run you mustang without headers or any kind of exhaust it would have no back pressure at all because there is nothing restraining the air that is coming out of your engine. however this doesnt mean that you car will be faster backpressure is important when you want to produce torque specially at lower rpm, That is why H-pipes produce more torque at lower rpm because they produce more back pressure! on the other hand x-pipes produce a little less torque at lower rpm but at high rpm the air flows a little faster producing more HP.. Hope it helps....
PS: this applies to any car, not only to Stangs...

 

thanks

 

Also it's a driveability question. Some people like the backpressure cause downshifting has more of an effect. Since I put my X on I've def seen a difference in that.

 

Well i have no H or X pipes and no back pressure.I have TRUE duals that run out no cats and dump at the rear.THe only draw back i have found is that it cackles when you let off the gas.

Im adding a set of flowmasters to help tone this popping down a bit and give the car a little more rumble.

 

mine pops when i let of the gas and i have all 4 cats and two flowmaster mufflers on it
will the h pipe tone that down??

 

how exactly is that? downshifting puts you at a fairly high rpm, in most cases high enough to benefit from the effects of horsepower more than low end torque

 

back pressure=bad....you dont want any. people can say you want back pressure for low end torque, thats BS. the thing people dont realize is, when using pipe thats to big, the exhaust gas velocity slows down, thus, creating back pressure.

 

I meant downshifting in normal driving to slow down not to get more power. As in everyday driving stuff, downshifting doesn't have as much of an effect to slow me down with my X as it did with my H.