Just curious about the most boost that could be seen with the stock cat-back system. Anybody have any numbers? I have a S5 with a 2.5" Bonez DP & Hi Flow cat with the factory cat-back system and pushing 10/11 Lbs. with all else on engine stock including the air intake. Have had a Apexi intake and cold air box to install for the last year, but with the car running so well, just thought I'd wait.
As I said, just curious if I can get a little more by the installation, or is it maxed out now.
Thanks

 

you can run 12-13 lbs. reliably w/ any exhaust (stock or not).... but your maxed out motor wise.... the engine can only handle that amount of boost (not to mention the turbo).... you will see increased power through the power band w/ an aftermarket exhaust, which will make the turbo spool quicker, and give you more torque.... so, performance wise, replace the exhaust..... to answer your question, 1 to 2 more lbs. is pushing it!

 

I've run 10psi max on an '87 with punched out pre-cat and main cat.
The rest of the exhaust is stock.
You should not see more than 10psi...at least on a Zenki.
The Kouki FC turbo run a boost controller, so you might get a little more boost.

Yeah, I cranked the MBC all the way up, so this is the same as running no WG line.


-Ted

 

My TII rite now is running 2.5" downpipe, midpipe, and race pipe with stock cat-back. I can only manage to get it a little past the stock gauge and it reads around .52 bar on my aftermarket boost gauge. I can't get it to go anymore... i may try a MBC later.

 

I was away for the weekend, so thanks for the replies. The G Force ecu upgrade moved it to 10/11, so I'll install the Apexi and cold air box and see where it takes me. Just a FYI- A FD pump was installed along with the ecu a couple years ago.
Thanks again