As mentioned, the idea of having a list of mods available by searching under REG or model of car would be really handy... bit like www.mstyle.co.uk
which I find very very easy to navigate around. Something like that would be pretty good I think but ofcourse, to have your own USP to it
Maybe the ability check how a certain item might look once fitted could be a good option - just thinking loud here since I've no clue on the cost and resources behind the development of this (presumably lots!) but I'd absolutely love to see how my car could potentially look by dragging / dropping the item against said car and seeing the finished article. I think this could help boost sales since but I presume it comes at a very hefty price tag!
Certainly interested in the website