[twodear]

I am of the view that I buy stuff for me to enjoy, not the next guy down the line. Having said that, I tend to hold on to stuff for a long time - resale value is going to be more affected by overall condition than whether it is original.

For sure, if you expect to want to upgrade in a few years then it is best to keep it original. If you've replaced stock bits with performance bits and bling, protect the original parts and keep them all together in a safe place. When it comes time to sell or trade, remove all the aftermarket items and return it to original - sell the aftermarket parts separately. Offering them to the next buyer may only give him the idea that you've done something bad and reduce value.

The biggest aid for resale though is to keep a full record of regular maintenance.