I don't race with a Rustler but I do have an old Traxxas that I do race with. It has been a couple of years and I am about to get back into it. If I wanted to race with Traxxas I would keep my eyes open for a SRT, Blue Eagle or LSII on ebay. Any one of these will beat a Rustler without modification. I was pretty competitive with my optional graphite chassis SRT and hope to be so again.
