Doesn't really matter which one you use...I've used a DynoJet and a DynoCom. DynoJet reads the highest and a Mustang Dyno reads the lowest. You really should look at 1/4 mi times and calculate the DA to get a better reading of how well the car is performing.

To give you an example, I ran my setup (prior to re-tune on an exhaust) in cooler weather, ~70*F, and hit 345whp on a DynoCom. When it was 94*F, on the same setup and dyno, I posted a 314whp.

C3 Pulley, LET tune, and stock exhaust on a DynoJet, people were doing anywhere between 333 and 340 but it was also 65*F . Every engine is different so it's hard to say which dyno is the best one to use. Also, realize that since it's summer, the numbers might read a little low because of the warmer air.