Also make sure the old plastic seats are not cracked. A couple of my seats were cracked and I could not locate a mystery boost leak until I tested the manifold side. Whalahh it was the seats. Also if you have TT injectors they run larger diameter (skinnier O-rings) than stock O-rings on the TT injectors which will crack the seats if pressed in. If they are cracked / older they also usually bond to the metal intake because of high engine temps. and make it a b*tch to remove (not sure if factory uses a sealant on these or not). I recommend some sealant when reinstalling. Also Didn't know APR made their own cup seals... good write up