Ok, first off, to upgrade and engine, you either have to buy a new one, change the pipe, change carb, or do port or polish. Since the duratrax stock engine is a piece of junk, I would trow it away and get another good .21 engine. I wouldn't get a .26 because they are not made for buggy and they have a lot of trque but usually die at higher rpms. Changing and engine is the easiest thing to do. Today I changed the engine on my Swift and it took me about 10 minutes lock tighting everything. An engine that I will highly recommed to you is the ofna .21 8 port engine. You can get these on ebay minus pipe for about 100 (new). The stock engine in that Axis has about 1.7-1.9 hp, if not less, and an 8 port has 2.45 hp, so it will make a drastic change.

But if you are really thinking about .26, then you can get some nice ofna Picco .26 for about 135 minus pipe in ebay also new, which has 2.7 hp, that will probably be too much for you, since you are learning to drive.

If you really need upgrades for the kit itself, just go to www.towerhobbies.com and search for them

On last thing, if you really want to get serious about this hobby, throw your Axis aways and get something like a Mayhem, kyosho sports, Swift or something like that. Good luck