mail order tune with high altitude

Just about ready to get a bolt on tune for my car and am going to go with madz28 or pcmforless but the locals here in colorado say I need a dyno tune and that the mail order tune wont be good with the hi altitude here, They say my a/f ratio will be way off, Is this true? I really dont want to spend $450 on a dyno tune for just my bolt on car in sig, And I dont have enough tuning knowlege or experience to tune it my self I'm kind of inbetween a rock and a hard place.

Both of those tuners mentioned are very good and have done cars all across the country, just specify your specific altitude when submitting your tuner sheet, they should be able to handle it from there.

So do they adjust the a/f ratio or just bump the timing up?

I don't know what parameters they adjust, that would be something though that the tuner can answer for sure.

Just waiting for some tuners to chime in, Do madtuner and pcmforless adjust the air/fuel ratio or is it just a timing bump?

I tryed emailing ion from madtuner but I keep getting a failed delivery notice in my inbox, I have emailed him before from that address but its not working now?

Talked to Bryan over at pcmforless I will be going through him since madtuner's email dosn't work. Anyway Bryan told me that he will be adjusting the fuel tables as well as spark tables So I should be in good shape with him. I will be dynoing my car before and after the tune and will report any gains from the pcmforless tune.