I was there... too. I thought I had a decent build, as you described. Until a guy with much less ran a second faster than me. I wasn't upset, I only wanted to learn the "why's". I don't count myself as a super tuner or anything of the sort. But my personal expectations for my cars and what I demand from them is what I learned from the past. I don't put my cars on pedestals, and I fully believe anyone can get the same results because I'm not special... LOL, and is why I said I thought the op would hit low 13's, or high 12's. I would except nothing less than a 12 second pass with his combo myself.
