Originally Posted by
syfi
Actually what Brian is showing is the delete of the resonator and replacing it with a "Y" pipe and a couple of 90s to get around the rear diff. My mod will leave the Res in place and remove the rear cats and H pipe for replacement with the "X" pipe. I recall seeing someone on the forum even replacing the cats with the x-pipe while leaving the h-pipe intact!(?) Supposedly the resonator has a lesser effect on the flow then the cats do, and will still help keep the drone down along with the x-pipe. At least that's my interpretation from what I've read. I still can't find an answer to my quest to find the right size for the x-pipe needed.
I'm really liking this discussion, as I am currently looking into how I'll go about it also. Although the X-pipe apparently produces better flow and scavenging and perhaps a little h.p., it may give up some of the low end torque that we all like. For all out race and 1/2 mile event(like Les), the better top end would be good, but for auto-x and daily grunt it may not be a good thing. I'd love to hear some feedback from those that have the downpipes and have added the X-pipe in addition to the H-pipe, or removed the H-pipe in favor of the X-pipe. Is it worth the time and money? Regarding the X-pipe size; Brians merge collector inlets are 2-3/8" I think, so the pipe going in would be 2-1/4" I believe. I'm going to climb under the car this afternoon w/ my calipers and see what I've got.
On edit: I also wanted to clarify. Les has graciously offered his shortened NW's downpipes to me, so I need to piece together the back half of Rob's DP's, and have the opportunity to throw an X-pipe in there if it's a no-brainer. I'm just not quite convinced yet that it's the way to go. Any X-men out there for feedback?