Hey you guys, had my G dyno tuned in February this year and it made 271 horsepower and 260 torque. During the months following I added an 5/8 blox spacer(got it used for the low) and a agency power single exit exhaust. I go and get my G retuned only to find out I lost about 13-17 horsepower and torque all thru my midrange and my overall peak went down from 271 to 266 and torque 260 to 255. Wtfreak!? Any body have any ideas? Could it have been the 5/8 spacer?

What year, what other mods? What exhaust did you originally have when you got the tune?

It’s and 05 6speed. I had a ebay exhaust when i got the first tune with test pipes and injen cold air intake. 2nd time of tune was when i added the spacer and agency single exit.

Could be a number of things. You went to the same shop for the tune and they're using the exact same machine? How long since you've changed the spark plugs? Did you use the same octane of fuel? What was the humidity and temperature difference between the two tunes?

EDIT: Wait a sec... you have a revup motor and you ONLY added the spacer without adding the MREV2 lower plenum yes? If so this is likely the reason you lost power, the spacer on that motor requires the use of the MREV2.

Yes same shop same machine same tuner same 93 octane shell gas, (oh i forgot to add i have the mrev2 installed since first tune), talked to tuner he also suggested spark plugs but was positive it wasn’t that because the power loss was only in the midrange. Spark plugs were changed last year in October so only have about 10k miles. Checked for clutch slippage and nothing. Everything else is the same only difference is oil went from royal purple to valvoline the spacer and oil catch can.