I had an e46 3series coupe and Modded the hell out of it. As someone stated above, I got a little over bluebook, but it sat with a for sale sign for a while before going to ebay. I didn't do it for the investment, I did it to personalize my car. I have no intention of doing performance mods to my TT, but I have a feeling once the cosmetics are done, I'll get the mod-bug again...