Ok. I have decided to get a Ofna MBX Pro. The only problem is I want a different engine, I plan to sell the stock one.

I've been looking and reading other posts and I hear the O.S. .21 RG-X (P) is a good engine.

I just need to know how well it will fit because the exaust and pipe or what ever connector the the engine combined with the engine costs, this thing is going to cost me $170+shipping.

So please tell me if you think this will fit nicely, and what I need to do to make it fit. Anyone with experience with this please help!