Yes but the point is that modding the car will generally be a money pit. Most mods wont actually add value to the car and in some cases, buyers will be put off. I've read lots of threads on here where people say they will only buy standard etc because there seems to be a notion that a modified car has had a hard life. In reality thats not always the case as is proved by many cs members. However, the potential buyer at the end of the day is more likely to be joe bloggs who is looking for mint standard RS's on autotrader.
If you feel like modding the car then go for it. Just ensure you plan ahead and factor in any related costs at a later date so you dont get stung. As mentioned above; alot of people keep original parts etc so they can return to standard when selling. Thats a sound idea imo and you can always sell the mods on here afterwards to cover any removal costs.