I just installed a corsa exhaust system and a volant intake on my 05 sierra z71. i have noticed that when i floor it, the trans doesnt shift down, rather it starts in a higher gear and accelerates slowly, what's up? please help me figure this out, thanks.

 

Uuuhhhh.... Is the MAF plugged in???

 

I'm guessing it does this around 40-50 mph??? It's just the way it's geared... Try turning on your Tow/Haul mode on...