RE: N-Rusty
Well, if you have the money, you might want to look at the TM. Although many people dont have the money for a $200 engine.
If you don't want to spend the money on that, then I recommend getting the CV-RX. You will want to get the Rotary carb version(Due to low speed needle location). And if you want to get the stock traxxas clutch, you will need [link=http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXLR79&P=7]this[/link] adapter. If you use the Traxxas clutch, you will also want to get the short crankshaft version of the CV-RX .18. This is a great engine, I have one in my Rusty, and the thing wheelies like mad.
There will be some trimming you have to do to your motor mounts if you get this engine(due to the huge backplate), but nothing too serious, and it is well worth it.