Those numbers are very realistic. About as normal as possible. I've never heard about a 1.32 gear for an Alpha, but I guess you learn something everyday.

Was your old gearcase also the shortie? You mention running a Mirage. Anyway. Running that prop height I would say that the Rev 4 is a good choice. The M+ might work, but it is a somewhat high prop height for a 3 blade. But if you can test it, do so. On all accounts, you will most likely have to start with a 19" to get your rpms up.

I was planning on replacing the stock exhaust with some EMIs and replacing the stock intake with an air gap intake to free her up a bit. I'm not sure how that will effect my rpms. I know it will give me some increase. Any idea what these two changes will net me?

boy that is an ugly prop no offense .

That really hurts my feelings...I was going to put a clock in the middle and make a necklace out of it.