I guess I'm somewhat curious to hear from guys who've owned a variety of typically heavily modded cars Modshack, GunKata, and others, as to whether the GTI is PARTICULARLY SUSCEPTIBLE to not getting even close to your money back.
For instance, if you go look at Corvettes or Porsche 911s on ebay, etc. and the guy has engine and exhaust mods (of a high caliber), he tends to leave those on AND seems to be able to charge accordingly.
For instance, an Akropovic exhaust on a BMW or Porsche is worth some $, LEFT ON THE CAR. On the GTI....not so much. My beef is that the vehicle at issue seems to be modded in PREMIUM (all APR) fashion, for almost negligible gain. I understand that all you guys are saying "that's life, brah" but it still sucketh for the seller.
Car seem to have different personalities and strong points, and some do a few different things/jack of all trades, master of none, or some truly are a master at just one thing.
So, going off of that concept, a car like an M3, Corvette, or 911 may fetch a better price with some and/or certain mods left on the car, sure, but again, it really only matters to the perspective buyer and is not necessarily the norm, nor a "rule" for the market. The reason for those cars being like that is their main objective is performance/hard-on cars, so they carry that with them no matter what.
A car like the GTI is a jack of all trades and to some people, it is simply a golf with a turbo motor and perhaps a 6spd, while to others - if it sat for 8 years and only had 200 miles on it, it would still sell for MSRP
It is truly subjective, but I think the main theme here is the buyer. What is the buyer looking for and what do they value. You will always get more for your car when you are selling to a specific audience FOR that particular car, plain and simple. So, if its some basic mods that cost the seller $3K for example, he can probably get away with charging another $1500 or so over what the car would normally retail for in a private sale, to another enthusiast. However, if he took the car to Carmax, or a dealership, or put it up on craigslist, the average joe is going to say - no way, its too much, I don't care what you've added to it.
To get back to the 911/m3/vette examples, that's like if I were looking at a 996 911 Turbo, and I found one that was chipped (lets say from the factory, X50 option or whatever it is), and has a beautiful and expensive Milltek TBE or Akrapovic, etc exhaust on it, AND a set of $4,000 BBS wheels on it, i would gladly pay $2K-$3K more for that specific car and those mods than a comparable all stock/unmolested car as it would save me probably about $8-$10K including labor, BUT again, that relies on ME and not the average buyer, as many have suggested, most DO NOT want to buy a car that has been modded heavily, if at all.