No problem man.
As for the headers, yea I notice a difference. I have no competition with GT celicas now. My competition is with the GTS. I can beat them in the 1/8 but not in the 1/4. Thats where their lift takes dominance, up top.
I installed it myself, very time consuming but not difficult.
As for voiding warranty. I couldn't tell you. I'm sure it voids some things and the dealer will try and use that as an excuse to void it. So it basically dpends on the dealer.
Keep us updated with whats goin on and whatnot.