I highly recomend the RB 928. It has all the power and torque that you need and way more!! I use the JP 2 pipe with it.

A great low and mid motor is the RB 728. The thing pulls like a bull. It does not have the top end like the 928, but for low to mid, it is very hard to beat.

I didn't read your first thread. Picco or Wasp .28.. I would go for the Picco.

If you want big power in .28 still stick with RB.