Exterior Modifications
I'll admit it, my car looks almost completely stock from the outside. The only nod to the aftermarket industry that can be seen are the Borbet wheels and the euro bumpers. I don't have any body kits, no rear hatch spoilers, no Zender side skirts, no bright yellow paint, no frenched antenna or shaved markers. Why? Well, the one of the reasons I bought a Rabbit in the first place is because I loved the way they looked. I still think the GTI looks great even in stock form. Whatever you do to your car is completely a matter of personal taste, but don't look here for instructions on how to install body kits or suggestions on what vinyl stickers look good stuck to the inside of your windshield.
There are a few things that I believe look really cool on the A1 GTI. 15"x7" wheels fill up the fenders nicely and provide a little more contact patch on the street. Euro bumpers get rid of the klunky stock bumpers that came with the US made Rabbits (but don't provide the crash-worthiness) and integrate well with the overall line of the car. The round headlight conversion from a later model Cabriolet looks killer on a GTI, but alas, won't work well with models equipped with air conditioning. My personal opinion is these few things are the only changes that should be inflicted to the outside of your car. After all, this is a GERMAN car we're talking about, and the Germans are not known for their flaming displays of showmanship.
Wheels
There are literally hundreds, if not thousands of different types of wheels on the market that will fit on the A1 platform. Before you go out and plunk down your hard-earned cash for a fancy set, there are several considerations that should be studied:
1) Weight: One of the primary concerns of chassis engineers is the reduction of "unsprung weight." What this means is the weight of everything that is not isolated from road imperfections by the vehicles springs should be minimized. This is one of the primary reasons that some wheels are so much more expensive than others, since the manufacturer has gone to great lengths to reduce weight while maintaining strength. Stock VW alloy wheels are relatively strong and lightweight, but most aftermarket wheels are much better.
2) Strength: A good set of wheels will take an incredible whack from a pothole and still will not bend. Those of lesser origin will bend easily and have you swapping your OEM wheels back onto your car. Another reason some wheels are much more expensive than others.
3) Hub-Centricity: The wheel should fit tightly around the wheel hub on the car. This is called "Hub Centric." A wheel that is not hub centric does not fit the car well and will lead to balancing and alignment problems later on. Wheel manufacturers do not make a different type of wheel for each different car's hub size. Rather, the company that sells you the wheels will put an insert into the back of the wheel that is made for your particular vehicle. The Tire Rack uses metal alloy inserts, while some other retailers will use plastic. Of course, metal is preferred - ask what type of insert you're going to get before purchasing the wheels.
4) Offset: This term relates to the alignment of the wheel off the cars hub, in to out. Have the incorrect offset, and your wheels may rub the outer lip of the car's body, or grind up against the brake calipers. Each different width of wheel has a different offset, so a 14x6 will have a different offset measurement than a 15x7 wheel. Make sure the company that supplies your wheels knows what the proper offset is.
Bumpers
The stock bumpers on all Rabbits/Jettas/etc. are ugly contrivances that were tacked on by the factory so the vehicles would meet US crash safety standards. They are heavy, and do not integrate well into the lines of the car. This is why the bumpers from European models are so popular, since they vastly improve the overall looks of the car. One thing to keep into consideration when purchasing these: they do not meet US crash specs, and if you run into anything with these bumpers, you're not going to get much protection - meaning sheet metal damage.
To see step by step installation instructions for Euro bumpers, click HERE.
Lighting
All Rabbits made in the US came with square sealed-beam headlights. Like all other headlights mandated by the Feds back then, they work adequately, but are not very powerful and provide mediocre dispersion. Salvation comes from the fact that the euro H4 setups are available for sale in the US. These are not sealed beam units, and therefore have replacement bulbs like most modern (i.e. '90's) cars do. The bonus part is you can change bulb wattages, and get headlights powerful enough to vaporize small animals in your path. H4 bulbs come in three basic sizes: 55 low/60 high, 55 low/100 high, and 80 low/100 high. The 55/60's provide very good lighting, while the larger sizes are overkill. If you must have the higher wattage bulbs, you will need to wire in a relay to power them. The 100 watt high beams will damage your light/dimmer switch over time due to current overload.
Another popular swap is to replace the Westmoreland two square headlights with the four round setup from the later model Cabriolet or early model Scirocco. This does add somewhat to the overall looks of the car, but it is not a straightforward swap like some would think. The front radiator/grill support is entirely different, the headlights mount if different positions (of course), and to truly make it look right, you have to change the fenders to match. The best way to perform this swap is to remove the old front radiator/grille support from your vehicle and replace it with one from a later model Cabriolet. This requires drilling out the old spot welds and welding in the new sheet metal. It is not horribly difficult if you have the appropriate tools. You can buy the appropriate sheet metal at rabbitparts.com or Oldskoolindustries.
Here's a good VW Vortex
thread about changing the front support:
http://forums.vwvortex.com/zerothread?id=2073102
Here's the old Phat Rabbit
Page how-to on installing the four round Scirocco
setup:
http://web.archive.org/web/20000916024100/www.frontiernet.net/~volvoic/HEADLITE.HTM