Here's a pic of the '98 GTi prior to any modifications:

'98 VW GTi 2.0L Ginster Yellow Bought new, 8/01/98 in S. Jose, CA

Mods

So far, I'm pretty happy with my car after 13K miles or so... it's definitely got some squeaks and rattles, but what can you do?

The most obvious change I've made is losing the stock 14" wheels and BFG tires.  I swapped them for some 16" TSWMotorsports rims and Dunlop 45 series tires.  Harsher ride around town, but completely worth it in terms of handling and looks... the change in both is significant.  Ride noise is not any more noticeable than previously.

I've also added the following: a Neuspeed ECU chip (small but noticeable torque improvement), AutoTech front and rear stress bars (very noticeable chasis improvement under cornering) and a 4-point harness.