Title doesn't really describe my question. I took off my intake and stood it on end and put it back on after a series of mods. Now it seems like it may have a vacuum leak. Can't find it though and it is minimal if it is even real. When the A/C kicks on it revs up about 300rpm and takes second to come back down. Never did this before I removed the intake. Any way, my porter sent me a ported TBSS the other day and I noticed a plug on the back that goes in and out about an 1/8". Whe it is out it has a red ring exposed. When in you can't see the ring. So today I check my truck to see if it has one. It does and that is where the brake booster hose connects. It was pushed in since it was standing on it while waiting to go back on. I pulled it out and pushed it in with out much change of anything. What the heck does this thing do? Does it need to be in out out?