Update by Tim Suddard to the
I've owned two A1 GTIs -- neither with the Callaway kit (which was, along with the Oettinger 16V head, a favorite bit of automotive porn for me back in the day).
One caution about the chassis: my second one repeatedly failed on me in the rain, once on Hallowe'en Night in 1987. My wife was pregnant with our first child, who was born six weeks later; the car died on a busy Southern California freeway on our way to an autocross. Pushing the car in the slow lane on the Ventura Freeway (which even then was so busy they cannibalized the breakdown lane to accommodate extra traffic) was, in the words of Tommy Lee Jones, "one of a thousand memories I don't want to have."
I finally determined the failure mode and the cause, and that's why I'm writing to you: the 1984 GTIs (and other Rabbits, presumably) had glue-in windshields, which were apparently a learning experience for the crew at the Westmoreland County, PA manufacturing facility. Specifically, many of these cars had voids in the glue that held the windshield in place, allowing for water to leak in.
In my '84, the water leaked in above the driver's left ankle. Unfortunately, between the ankle and the windshield was the relay box. In particular, water leaking in filled the fuel pump relay, which caused it to short out and fail.
About the third time this happened to me, I had one of those flashes of insight brought on by the inhalation of too many Castrol fumes, or too much Newcastle Brown Ale: What would I do if this were one of my British cars?
Why, old bean (I thought to myself), I'd lay hands on a tube of RTV and seal up the fuel pump relay so water couldn't get in.
Worked a treat, till I sold the car some years later for a 1982 280ZX -- first year with "Nissan" badging and with rack-and-pinion steering. (I sold THAT one to pay for the paint job on my 1967 Alfa Romeo GT 1300 Junior. As my son once said after giving him a hard-won pearl of paternal wisdom, "Wow, Dad, you really did a lot of things the hard way.")
In your case, I'd recommend testing the windshield gasket for leaks and, if no previous owner has fixed them, consider replacing at LEAST the gasket/glue and possibly the windshield, if it's at all suspect. But the irritation of having a car quit on a rainy day is one thing; the possible effects of intermittent and insufficient fuel supply on a turbo could get expensive quickly.
