Yea, upgrading to a 3.3 later would be a good idea but getting an OS .18TZ would be a better one because it is cheaper and more powerful. The nitro sport would not be able to keep up with the revo and it would also get run over by it. If he gets an OS.18TZ, then I think you'll have a hard time keeping up with him. If you want to get a new engine for your revo I suggest the OS.18TM, it is a direct drop in and it comes with all you need to get it running in the revo.