I called the boys at Granetteli and they said that there unit is a lot faster in measuring the air coming in and sending that info to the computer , when used with a CAI and a custem tune this will result in an extra 6-10 rwhp, with headers,CAI, tune 7-12rwhp. I called lingenfelter and gave them the same Question and there tuner agreed with this, it's not in the flow but the speed of info transfer!!! I'm going to test this when I have my headers installed and have them do the tune the same day, I'll see what the dyno says using the OEM and aftermarket unit I'll post it up as soon as I find out. Have any of U bought one off these, seen any difference?
