hey guys does anyone have any experience with Grimmspeeds port and polish services?

Specifically tgv delete and the ordering process. They do have a refundable core charge program, my question there is what does that core give me? do i get a set of tgv deletes from them and then i send them mine to get the core?

i emailed them this morning but have yet to get a reply, so i figured i would find out if anyone has any experience?

thanks