Haven't decided to do anything just yet, but was wondering before I do what mods have had the most impact on your insurance rates or how they affect coverage.

Thanks!

 

Not much to do on a non-S....
But there is no need to tell them!!
I don't think I have ever heard of anybody getting a quote change until their cars are so highly modified that they switch to collector's car insurance (because of age((not us)), or massive mods with huge $$$$, more than most any S I have seen (perhaps 100% custom motor ((head, pistons, etc)), interior, etc), but a few,,...so called agreed value policy's...
If the car get totaled, many places will let you strip aftermarket parts....or give you the cost you spent on the parts with an actual receipt IF you are lucky!! Stolen, no idea...

 

I see Suspension in your future.