ORIGINAL: yakfish
the CVR is the best bang for your buck. you can easily find one for under $100. I had one in my mt2 and it was quite fast. it has alot more power than the stock .15 engine. I have a TZ in my RC10GT and I don't think the power gain over the CVr is really worth the money. but both are excellent engines. you could also try to find a HPI 18ss on ebay. they are very nice engines. I had on in one of my other cars and it was one of the easiest engine to tune that I have ever had. If I was you I would go find a deal on ebay for the CVR but thats just my opinion.
The difference between the TZ and CVR is huge.. The CVR is 1.3hp and the tz was dyno tested for 2.28hp. I have the TZ in my MT2, its extremely powerful. Pops the wheels up easily. I can do around 55MPH on 15/49 gearing.
You will need a lot of drive train upgrades in order for the MT2 to handle the power of the TZ.