Well I've always used tr6 at .030 from a pulley tune which i believe i did .035 to a tvs to a whipple. Never any issues an change them yearly with the oil and everything else. Strap mark looks perfect, the real question is how long do you plan on leaving them in the car? If the answer is several years then yeah i would go with $100 plugs. I might try the tr7x this year just to see if there's a difference. If your drag racing every weekend i would do frequent changes regardless of plug choice.