Don't think the chassis has a problem with more power though the drivetrain might. Main mod for improved lap times seems to be 18" front wheels with modern bike tyres to give lots more grip. There's a few folk on the forum have been out in sprints, hill climbs and some racing too. The extent of the tuning has to be down to whatever the class rules are and in the UK the M3W lies somewhere in the no man's land between the MSA who administer car racing and the ACU who do the bikes. Which means that if it's a car due to the big engine it needs a cage, full harness, Nomex romper suits etc. While the following weekend it's a sidecar outfit due to the third wheel and you need leathers, no belts and a passenger. I'm sure there's a bit more detail to it than that but that's a taster of some of the issues.