Ok so I can’t tell if it’s working or not. I have an hks on my speed 3 and I put one on the 6 as well. The one on my sp3 is loud. It’s actually annoying in my opinion but it works great. The one I put on my 6 I can’t hear it at all. Even if I try. I took it off and it holds vacuum. I checked vacuum going to it and there is plenty. The main thing I see different is location on the piping. I have CS FMIC on both cars but the sp3 is located before the core and the Sp6 is located after the core. Any good tips to know if it’s working or not?