Has anyone installed the magnaflow true x crossover pipe into their stock h pipe? I think its part #10791?, where you cut out the "h" section and weld in the magnaflow "x". If so, what gains in hp and tq did you get with that mod alone, or with an aftermarket exhaust? I want to get a magnaflow w/cats and trying to save $ by getting the true x instead of springing a lot more $ for the whole x pipe.