I spend an inordinate amount of time thinking about what I might do differently - upgardeitus and all that - but, ultimately you get what you get and make the most of it. One of the best things about my first Caterham was the home build. I also loved the flared wings and 'classic' twin webber's. And it was a hoot to drive. I got my used standard Zetec here in 03 and, apart from changing the wheels (16's to 14's) have done nothing much but drive it - 8000 miles in 4 years - and it hasn't missed a beat (I've missed a couple though...).
Having said that, I agree with Brad, longer 1st gear would be good. And throttle bodies, bigger brakes, hot cams, lighter flywheel... Help :banghead: