I had a local shop tint my front windws to 20%(that matched the factory tint perfectly). With that & the addition of in-channel vent shades, my vehicle stays noticeably cooler & needs a lot less A/C.

Mine did not need the felt mod & has not scratched the tint at all.

20% is not really legal here(upstate NY), but I have had three vehicles done that way & never had a problem.

~John