It will help if the aftermarket parts are named and described, possibly with pictures or a walk around video to show details and condition.
When aftermarket parts are added, it's usually (just like with guns) an effort to improve certain features. Just the fact that such add-ons exist is evidence that there's a market for them, and many prospective buyers will consider them a plus. Having them already installed is another plus. When describing them, avoid the term "aftermarket parts", and refer to them as "upgrades".
My Grandson (21) has extensive knowledge of bikes and their values. I'll show him this post when he's up and running...
Probably a lot later, he sleeps very late an Saturdays.
Greg