I read the Wiki a few times an understand it for the most part, but the one part I can't seem to find is an explanation of why you cut the pipe off, and re-weld the muffler back on. Does a shorter pipe affect performance? Is it really necessary as part of the de-restriction process?
I'm also wondering how much top end to expect to gain (basically stock V1) vs. how much low end I'll lose with the restriction removal? Is it worth it?