Hi Bob 1, There are three seat shapes available to order, Tillet (Race), Tillet (620 Carbon) and S-Type leather. Tillet (Race), as fitted to academy cars, are available in either kevlar or GRP, these tend to be tight fitting but I have heard it said kevlar are slightly more comfortable. S-Type leather and Tillet (620 Carbon) are more suitable for larger drivers. Comfort is subjective, I for example prefer Tillet (Race) over S-Type leather for comfort. 2, The springs fitted to the front dampers is all that's different (Sport to Track Suspension). It's actually cheaper to buy the springs from the parts site and swap them if your building a kit, especially if you sell the standard items. It's much like the carbon indicator mounts, which are cheaper from the parts store than to order with the kit. I am sure there are plenty of people who will tell you how much better / worse they are than the standard spec. I personally would spend the money on getting the car flat floored and the geometry spot on first. Sport Suspension is standard 420R spec, and that has adjustable platforms. Race Suspension used the 620R spec dampers and springs. (FYI Road spec (S models) is the same as Sport, but without the adjustable platforms) 3, Noise is measured static and drive-by, the IVA static noise test is actually stricter than Bedford Autodrome, which is generally considered the most strict nose level track in the country. That said drive-by can be a problem dependent on the mic location and track. For example Brands can be tricky, but I have seen plenty of 420R videos on Bedford. Finally it also depends how hard you can push it, so the same car with a different driver can have problems. I went with the side exit, if I start getting problems I will upgrade to a Raceco side exit, mainly because I don't like the look of the rear exit. 4, I think the main hidden difference between ordering with or without weather gear is cars not fitted with factory windscreens aren't fitted with wipers. So in general without weather gear is a brave initial option. The hood is useful if you ever leave your car outside overnight, so it's not something I wouldn't be without. Half hood for driving obviously ;-) Hope this helps PS - think about the track day roll bar ;-)