If I'm not mistaken the 4.9 final that ATS makes is only for the B16 tranny, and not for ours. Not sure though, you may want to call for applications. Also, I think ATS in addition to Honda also makes a 4.7 final for our cars??? You could also get the ATS 3-4-5 gears, which I would actually recomend, as our cars already have pretty good 1st and 2nd gears. I guess it's just a matter of what and where you're using them. With a much shorter final drive, you'll be shifting much more, or faster I should say, so if you're planning on doing some sort of forced induction later on, it's not a great idea...Also, at some tracks local to me, Miami Homestead in particular, with a shorter final drive, I find my self down shifting in places where ordinarily I wouldn't...All a matter of personal prefference and application purpose

Well, either way, this is not something you should attempt to install yourself. Especially if you don't have a gear puller, a snap ring pliers, and a very good know how of honda trannys. Not only is it a bear to take out and put back your tranny, it's far worse to disassemble it and reassemble it. It's a nice mod if you're going into your tranny already for like a bad synchro or something, but otherwise will cost you probably close to a grand in labor at Acura assuming they'll even do it.

Later,
Aj