.....if you still have the borla's off the 98 s281 that you once had, take a picture of the mufflers and post them. I'll do the same with mine. When XMP installed the XR1's, there was a noticable difference in the size of the two borla's. The current mufflers I run are a straight through shot, meaning you can hold the muffler up to eye level and see straight throw to the other side. I'll do some quick research myself and let you know what I can find.....
visually these appear to be the same size as the borlas on my brothers 96 cobra (which is SIGNIFICANTLY louder than mine) i contributed most of that to the fact that its DOHC. but since it was a borla catback, i am not sure if they sell a xr1 catback, i know whatever mufflers come in the cobra catback is what its got. i just need to know how to make mine that loud, short of swapping a cobra engine. we are both running the same dr gas offroad xpipe as well