If you just installed the spacer... It took me AT LEAST a couple of hours the FIRST time... mostly from being overly cautious and not wanting to jack up my engine!?! (mostly in the disassembly, then re-torquing sequence!) but it CAN be done in 30 minutes or less... just don't mess with the rear hoses at the plenum TB and it's a piece of cake! I added the Copper Iso-Thermal upgrade to my spacer.. it took about an hour tops.. and that was involving the removal of both the upper AND lower plenum and the Throttle Body.. and I added some silicon PVC and Breather hoses while it was all apart also!
As far as change in response or power... DON"T FORGET TO RESET YOUR ECU!! this is key... wiping out the old learned A/F maps on the ECU after installation of this major intake mod are a MUST... the Air/Fuel ratios are DEFINITELY going to be different with the spacer... better air flow at the intake... different fuel mixture needs!
I think after you reset.. you will pee yourself with delight
from the DEFINITE difference in response throughout the whole power band.. I believe others that have installed the 5/16" spacer will agree that this version gives good results in the mid to high RPM range of the power band.. the 1/2" is more for the high RPM range.. not so much the mid range.. pretty much where I tend to spend most of my time.. not so much flat out!