The t1r 70EM Sparrow is the one that has the best gains the one jdm yard has in stock is the 63mm sparrow.

I had the apexi n1 on my car, it was loud and droned a fair bit, didn't do much for the butt dyno it was almost as loud as my straight pipe but it had 100x the drone haha. Nice looking piece but that's about all it's good for a cheap exhaust. HoweverI saw your one for sale looks like a custom one with a apexi muffler.