what groups are there for a track day as i want to use my mk4 when its done as a little track day toy for some fun but dont want to be pissed on by all the cossies etc...

its only going to be either a

1.8/2.0 zetec with exhaust and k&n...

or a 1.6 cvh, with some minor head work, 4-2-1 manifold and exhaust and k&n...

whats the best group to go in to suite me?