Twin motors might be able to be done......Mortars on the other hand I would not go more than one. The have a lot of recoil. You would also have to work on servos to work the sighting system. Would it be Lipo?
Frickenjoey, Rolex, you really are a pair of hilarious guys..... that little tirade had me LMAO !!!
Twin motors is possible on a revo, but it would mean a dual motor plate and an esc that could handle twin motors (HPI E-savage springs to mind for the ESC as an example) plus the batteries would have to stand the power to them. I do not see the conversion being a problem though. It will just require a little research and some "tinker" time to get it set up right.
Also, you may want to consider what type of battery you want to run and also how much power you want to put to them.
Kershaw designs makes twin motor conversion. They are said to be close to a entry level brush less. The double 700 ho motors are great. All the reviews that I have seen on the double 900 ho say they overheat the ESC. The only down side is that it give your car a higher center of gravity, hence more rollovers through tight turns.
And on another note they send a double motor plate that bolts right to you e revo tranny.