Clicking from Head installation?

[SlowStang2]

I couldn't just have heads installed and not have a worry in the world could I? UGH. I had a mechanic put on some used gt-40y aluminum heads on my stock block. There are no fluid leaks. BUT there is this clicking noise coming from the passenger side of the engine. I'm not sure if it is an exhaust leak, for it does not sound exactly like one. I do know that now it seems like the car is harder to start. Especially when its hot. That is what makes me most nervous. Theres nothing worse than being stranded in a far city with no tools or knowledge of what this is. Is this harder starting normal with swapping heads? The car runs fine during cruising speeds(no bogging, no hesitation etc) AND WOT. I mean, I can feel the speed and gains with these heads, so what could the problem be? OH! I do notice that in 2nd gear(only time ive noticed it in) the clicking gets harder/louder as if it was closer to ME than it was before, during WOT, but still no performance loss. I'm begging everyone on this one. I have to drive a lot of miles in the next 4 days, so help would be very much oblidged. I've seen other "clicking" topics on here and stangnet. I'll goo look there for answers as well as here since I have provided personal info.

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94' Stang GT Convertible --Cobra upper&lower, GT-40Y Turbo Swirl aluminum heads, Mac cold air w/K&N, BBK equal length shorties, BBK offroad H-pipe, American Thunder cat-back, BBK T/B 65mm, 24lb injectors, Pro-77mm MAM, pulleys, aluminum driveshaft, 3.55s, Steeda Tri-Ax shifter, adjustable fuel regulator 14.4@100 MPH on G-tech;96 at track. (Sad, i know. This is with the stock heads)