I need gearing help. Here is the situation:

Need: I need more top end speed.

Setup: Tekin Pro4 3300kv (540 can), Tekin RX8 (using 20/30 timing). I'm running a 63 tooth spur and have tried a 15 tooth pinion (not enough top end) and have tried a 18 tooth (Decent top end, could use more, having major heat issue though). Running 2s 7.4v lipo

Track: Medium size indoor, large straight away, some small hairpins. Any car can blow by me on the straight.

My question is, where am i going wrong? What can i do to get some more speed. Before I buy spend another $10 on a pinion, i want to get another opinion.

My suspension is perfect and i like where it is.

Thanks Guys