I'll probably get flamed on this, but I recently added the AFE box and proguard 7. I also have a torque tube. I have noticed that the filter minder now pegs in the red zone, whereas before it barely moved. Not sure if this is due to velocity of air past the new air filter mounting location, or the proguard 7 is more restrictive. This doesn't happen with the afe box on my duramax. Also, we just finished up some track testing last night, and did back to back with AFE box and with stock air box with 5000 miles on stock air filter. Net result: ET and MPH were EXACTLY the same for each (2 runs each). And I mean exactly. all within 1/4 mph of each other. I like the whistle, and it looks nice, but wondering if the $400 now was money well spent...