Its funny, we just got a Seat Leon thats done over 60k and it squeaks and rattles less than my brand new ED30 and 10K GTI
the quality of GTI and E30 is ... sporadic. Some people have no rattles whatsoever, I lucked out.
I, like Gaz here, have squeaks and rattles in my E30: center of the dash, somewhere in the instrument cluster from time to time, but particularly - rear seat. I've been in an acquaintance's Skoda Octavia which he treats mercilessly, its done 140000km, but it does not make a squeak. I've been in rental Lupos that were silent as a tomb.
GTI/E30 is pretty nice car, and you can mod it to your heart's content almost indefinitely and for reasonably low money (in Britain, that is, not where I'm at). You can make it go 130mph in a quarter and beat M3s, AMGs, tuned 335i's.
Personally, Porsche will be Porsche, whether it has more bhp than Golf or not. Porsche is yardstick for a sports car. Golf is a hatch.
(I have E30 Oettinger Stage 2 plus downpipe plus KW V2)