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.