Just spit-ballin' here -
There were a number of different tests people have talked about recently. I have a few I want to try personally. I'm even going to color a car with marker instead of paint for weight just to see for myself (someone else around here seems to do that with good results). ^^^^^^^
1) Try a new body design. I've been looking at some pictures that others posted and it gave me ideas.
2) Try re-weighting. Mine are only taped in so it is easy to do; then re-adjust steer.
3) Try a new bend on the DFW. Lots of discussion on that recently.
4) Try a new prep method for your wheels. Saw someone using 2000, 2500, 3000, etc to polish bores.
5) Try repreping your axles with more precision. Use compressed air to blow off contaniments.
6) Try a new COG. Left to right and side to side. Saw a new "tool" to help with that.
7) Try changing the height of you car above the track (raise or lower the fron end, rear end, etc.)
8) Try buying a whole car from John or JBD and disassemble it to see what makes it tick.
9) Try keeping a log with car setup and statistics and look for trends showing speed.
10) Try chasing the wife out of the room when she is badgering you about this hobby - so you can think.
I have the exact opposite problem. I don't know when I'm going to find enough time. I know I'm going to ruin wheels, wood , and axles, but I could be doing worse things...