While it actually also soften the sound, - it will allways make more power. -regardless backpressure or not with 2.5 inch or 3 inch.
X-over is better than H-pipes. -x-over acts like a little 'turbo' -making vacuum, everytime an exhaust pulse passes the X..-thereby sucking the exhaust out of the other bank. -this cycle is endless, -ofcause it won't make 150 horses extra, but it WILL make more horsepower even than with open headers.
