8.1L suburban 4x4... bone stock 107K miles. 17.3 @79.9 mph.

Installed Volant cold air intake with ram air scoup. 17.6 @ 78.3 mph.

Gibson cat back exhasut, super side sweep. 17.8 @ 78 mph

Hp tuners torque management delete, throttle delay delete, and drive line protection. Runs real good....

Truck set for about month and half, battery got unhooked as well

Installed... JBA long tube headers, with optional 3" down pipes, JBA plug wire, and new plugs. 18.4 @ 76 mph...

So, Is the computer screwing me up this bad? Bone stock it dynoed 238 whp and 311 lbtq which everyone said is low... its rated at 340 / 455 at the crank...

What do i need to do now?

 

sounds like you need a good in person dyno tune for that beast.

i cant believe it gets slower after every mod. that has to **** you off!!

good luck with that.. i would use that google and see who does custom dyno tunes in your area, or give wheatley or nelson a call... definately sounds like you need a good tune.

 

lol... im not amused. thing is it feels stronger about half throttle than wide open.

when We played with the Hp tunes it ran well, but ill admit i have no clue what im doing. from googlen the parts i have should put it about 400 crank hp and 500 lbtq. As it is right now its freaking 2.6 seconds slower than my wifes datsun. Her armada runs 15.8's with 300 hp and 370 lbtq... bone stock. Weight on the armada is 5900 lbs the suburabn is 6850...

How do you know if a 4L80E is slipping?