insurance companys dont see things as 'sus' they base there premiums on facts and nothing else, remember with mods, tell them about major things but dont go into to much detail anything that can be removed quickly,
as far as qoutes i am 21 and was qouted around $700 from memory for full comp including most modifications thru just car.
but try $3500 for full comp on a 2000 WRX for a 18yr old, been there done that, not fun.