hey mate!
Yeh a mate of mine has an mta4, pretty much the same as my MGT, it came with the .21 and it goes pretty well.... its a little bigger than the savage(wheels and stance,skight overall size and actually has a bit more suspension travel at the wheels anyway)... His doesn't pop wheelies as such but with harder springs or heavier oil it wouldn't be far off...
I have a port an polished HPI .25 (savage motor) in my MGT atm and it does pop wheelies with the right blip, but not anytime, again, pretty soft dampening... The two side by side my MGT has a little more all round, but surprisingly not too much...im looking for a .28 or bigger for my next mod.
hope that helps!

cheers, Adam