[Hi Volt]

Well it has been a while since the mod, 1200 miles and one drag race. Obseravtions on my truck; first, this does pick up bottom end performance, no question. Top end performance is a given with more air flow, highway travel rocks ! Extended highway mileage seems up, city seems the same.
I regularily drag race this truck at the track and have logged over 200 passes. I have a good feel for what the truck will do and can usually make consistant passes within 1 or 2 hundreths of a second. I just came back from a race this last weekend and have calculated the improvements. I was able to find records of passes made in very similar weather conditions ( temp, humidity, barometric, all used to calculate corrected altitude ) and came up with the following repeatable numbers. My 60' times dropped by a close average of .147 seconds ( quite substancial) and the ET picked up by an average of 0.41 seconds with a trap speed improvement of 1.48 MPH. All these numbers were averaged over 4 passes and did not vary on any pass more than 5 %. The average corrected altitude was 1800', so more would be present at sea level air conditions. For those who do not race, these numbers represent bottom end improvements as seen by the 60' et's while the higher trap speed represents top end gains. The overall ET gains are a combination of bottom end and some top end gains. Using a HP factoring program, it is calculated that a gain of 17 HP was required for what was recorded. I admit the numbers sound large, but on a cool evening slamming the throttle at 40 MPH will set my head firmly into the headrest ( never felt it that much before). Now keep in mind that these improvements happened on my truck as I definately needed more air from my measurements. On another note, I am not really heavily modified either, K&N drop in, headers and a 2 1/2" single output cat back exhaust. I am confident that the exhaust modifcations caused more scavenging of the cylinders and the resultant undesired WOT engine vacuum. Those trucks with bigger exhaust may require even more air than I do ( there will finally be an upper limit ), as well as any SC vehicle will definately benefit from less air restriction. The CAI systems provide more air, but as some have seen effect the MAF in a negative way, this mod definately does not mess up the MAF. I used a 2" hose for more air, perhaps a larger one would have a bit more improvement ? however the vacuum gauge said it shouldn't. I may put in a second one for a test. It is really easy to go back to the factory restriction as well, just plug the hose! This will allow back and forth tests to really see the difference and discount any other possible effects. This turned out to be one of those rewarding mods that cost next to nothing ( less than a buck and a half per HP, wish I could spend a couple of hundred this way ! but in all reality this is most likely the practical limit for this mod.)