No idea what seperate mods cost me, but in total: £498, 26 yrs old, 5 NCB, mk5 Golf GT TDI, colour coded bumpers,TDI tuning box >BHP approx 20-30BHP. Thats with Sky Insurance - forum sponser.
I think it's hard to give a specific cost per mod. Everyone's situation is different and no two people's insurance will be the same. Best to just ask the insurers tbh