Blowing cats but don't want test pipes? Move them down

NissanTracker

So update on this. Did get the cells Tig welded. Came out great. Like before with HFC's, i did lose some low end power due to the more open flowing exhaust with the supercharger (SCI). I did put a 370z VLSD into my HR nismo and did gain a bit of response due to the final drive. Not as much as I hoped to make up for the exhaust changes.

(VLSD change was really to get rid of the bearing noise that started after playing around with launch control on Uprev and thought why not go for the 370z with a high FD.... )

These superchargers apparently love back pressure in lower rpms. I'm in the middle of a fuel return install, but I'm thinking of adding a boost activated exhaust valve to one bank of the output of the Motordyne muffler.

Going to have it partially open in vacuum and try to set it up to open completely at around 4-5 psi.