What would be the best cost effective handling improvment for my standard mk3 golf gti 8valve? and can people who have already invested comment on whether it was money well spent and also if these improvements have compromised the comfort factor? and finally thoughts on the handling differences if any between a standard gti and other mk3 golfs.
Your first step would be to make sure your tyres are in good condition, all the same tread pattern, inflated properly, and the right size.
Then check all the suspension bushes for wear and replace anything that looks or feels worn. You can either replace with VW standard ones or go for one of the makes of poly bushes. If you go down the poly bush route you really need to replace then all except the front crossmember. Poly might affect your comfort slightly.
Then get the car aligned properly, this can make a big differance.
If you still want more then it all depends on how much more. If you want a lower stance with a slightly firmer ride then go for lowering springs and shocks. Stick with a brand name. This shouldn't compromise the ride quality too much. If you want to go the whole hog then fit coilovers, price ranges from £150 ish for height adjustable only up to about £1000 for height and stiffness etc adjustable. You get what you pay for. Hottuning ones are about £150 and are about 30% stiffer than your standard setup which is a pain during normal driving, also as Wayne said there seems to be some doubt that they last the distance. They do have a 2 year warranty though.
If you want comfort steer clear of the cheap coilovers, but if you have deep pockets then go for some mid range adjustable ones.
Remember if you change anything on your suspension it will alter the whole suspension setup and you will need to get it realigned.
If you still want more after all that you can look at anti roll bars and a more aggressive alignment.
Paul