It seems like mine does, after a hard acceleration and letting go the gas, the car stays in lower gear for may be 2 sec and then upshifts. Is it normal?

 

yes

 

yes, but if you upgrade with a Grounding Kit (i recommend www.groundinggear.com) then you will notice much better shifts and quicker response. It will feel smoother all around and you'll love it, promise.

 

Yes, it's normal and chances are when it happens, you've been somewhat aggressive with the throttle. What the tranny is doing is waiting to see if you're going to get back into the throttle and if so, it will hold the gear instead of doing what most autos do, which is upshift the second you let off the gas.

 

+1

You can read through the 350+ post here https://g35driver.com/forums/reviews/55081-gordgee-s-groundinggear.html

Mine are on the way !!!