I really don't notice much of a difference even here in So. Cali (Today it was 94) , I have the Stillen 2 core radiator,deep oil pan, a flex a lite exsternal trans cooler, a motordyne planum spacer and I eliminated the mechanical engine fan (It would'nt fit with the bigger radiator anyway, did my own fan mod utilizing the stock 6 speed manual dual electric fans). Just drove from Vegas Monday, average temp 107, highest temp 113 A/C set at 77, cruse set at 79. New cars are real sensetive to heat or cold variances and detonation, anything done that maintains a 200-210 deg. temp range helps.

 

Only when the A/C is on...

 

try adding a coolant control valve(CCV) and a lower plenum iso thermal Gasket, helps quite a bit ,i have both of those mods .My buddy just has the md iso thermal plenum spacer,,there is a big diff in our ,plenum temps

 

Don't really drive the car too much out here, but the couple times I have it's definitely felt a bit slower.

In a place like Hell a.k.a. Phoenix Arizona, would a cold air intake be recommended or best to stick w/ something like the stillen airbox?

 

Its simple physics… cold dense air has more O2 molecules… oxygen is needed for combustion, the more oxygen the better the combustion – so long as the a/f is proper you will have more power… hot weather = expanded oxygen molecules (less per any given volume)… this is why ppl go to great lengths to make the intake air as cold as possible (Motordyne Isothermal kit, cold air intake, iced plenum, etc… and various means of dissipating engine & header heat)

So yes, when it’s hot outside you will feel a bit of power loss compared to colder ambient temps.

 

i have noticed the same thing.......its been the same here as far as temp goes about 80f-90f