I went to the track a couple nights ago with my 94 Z28 M6 and I was shocked with my 107-109 mph trap speeds. The track is between 4K' and 5K' elevation in Utah. The only mods to the car is a K&N panel filter in the stock air intake,
punched cat and TB coolant bypass and a Shark Nozzle kit with 61N and 38F jets (told by NOS that this was 125 shot) out of four pass I trapped 107, 108, 108 and 109. on all the passes but the 109 pass the clutch was slipping so bad it would touch the rev limiter (Nitrous is on a window switch to shut off before the limiter) in 2nd gear before it would grab, those passes were 13.3, 13.3 and 13.5 the one pass the clutch gave me no trouble I only pulled off a 2.0 60' time and ran a 12.92 at 109 mph. Is this normal for being at this high elevation?

 

With a 125 shot, I say yeah thats about right.

 

with a 150shop on a 94 stock lt1 6speed.. only gears slicks and catback
i did a 12.666 at 105 at 4000ft
and a 12.9 at 111mph