Right!
Sorry I didn't spot this earlier, Great info about the Leggy and S3, both great cars, I have only ever seen the older model B4 on track and I have seen the S3 and passed it and lapped it!
I beleive on the road they would be more or less equel, the fundimental flawes in the drivetrain and chassis are very well masked be exellent ESP system, The A3 was not designed to have a big engine and AWD hence the Haldex not the prefered Quattro, But ESP doesn't suit the track, it applies the brakes and slows you down so much! (same as my golf)
Were as the leggy is designed to have it's big engine low down at the front, and it's gearbox behind it driving the Ideal symetrical AWD system,
The results as witnessed by myself at mondello is that the S3 seems to be very front heavy, seems to want to sail straight ahead when cornering I have never seen it cock up the rear wheel (which would indicate good front end grip like an integra for example) she gets good drive out of the corners and the brakes seem very good!
While the Leggy seems more tail happy, arse out is a regular enough site mid corner, So it would be trickier to drive but that shows better balance, So understeer wouldn't been such a big issue from what I have seem, The AWD on the leggy would work in such a way that when you plant the throttle when the arse is out then she'd pull straight in the direction that the front wheels are facing, so it just a case of not panicing when she does go out, (keep her lit)
So to clarify, the two cars would be equel on the road dew to the ESP on the S3 I do whole heartedly beleive the leggy is a better car on track and on the road in the hands of a very good driver!
To optimise your car for track,
Drop her abit (I think you already have that sorted)
Adjustable rear anti roll bar (set to tightest for the track and soft for road)
Jomo geometry setup, (hugh difference)
Mintex 1155 or Ferodo 3000 or EBC red/yellow on the front and fresh properly bled racing spec fluid (Go for brembos

) If you have good pads just keep them and use them again!
That's it, Total budget for above (not inc lowering) would be 700-800 I'd Imagine
Next open day is paddy's day next march!, there is usually one at easter (about a month later) aswell, so book in for paddy's day for practise and easter for your challenge!
Best of luck!
Dan