LRP X11 in 10.5 flavour, because the series I run my SC10 in has a 10.5 limit. Its perfect because its just a fraction too much power for the tyres to handle, so drive at 90% and you're fine, push to 100% and it turns into a snarling hooligan machine.
It really teaches you how and when to crack on during the lap before biting you in the arse.
