Yeah, not sure what to make of it. Negative stories get amplified on the forums. Some say it's been great, others not so much. APR gave me the impression it was certain cars/ECUs and it was addressed. I had APR stage 1 in my last car and loved it. Either way, I'm also considering Unitronic as the gains are similar. I test drove a car with a Uni intake and possibly a tune. Felt pretty good.
GIAC - haven't seen much mention or info on them. Revo - no dealers near me. Cobb - Sounds good and has a shop nearby but the gains aren't as good, and I've heard conflicting things on their hardware.
So based on HP and torque gains it comes down to APR or Unitronic.