I'm also wondering about this too. Betweent he WS2, SP2, and the RS*R exmag. My coworker has the RS*R for his 240sx. It's kinda loud I think, not really loud, but it got big ass pipe 80mm and a straight through muffler. For honda/acura, I think the piping diameter is smaller, 60mm.

I'm kinda lean toward the WS 2 since I can get it for $430, SP2 for $480, and RS*R is the most expensive of them all $550 I think