Just installed Richie's STB today. Only took 20 minutes, breeze.
Before driving:
I have 1/2 spacer, but the bar clears the plenum at the lowest position with plenty of space. I closed the hood to test if any part of the bar touches hood.Both brackets on two sides do touch the foam or insulator but still far away from the material of hood so not neccessary to worry about it.
Driving impression:
I did not expect too much improvement since couple of users said they can not feel much difference. I would say I can definitely feel it. My car responds much like S2000 in corners and you can feel the increase in body regidity as well. I initially thought the plenum might rub the bar a little and make noise due to engine twist caused by torque, but no, there is no any noise,at all.
The weight of the bar itself is very light, probably less than 3 pounds including two brackets. I strongly recommend this mod.