Got a question related to boost.

If a car dyno-tuned (flashed) with a 3" TBE and an MBC - and of course it runs. I went back to the stock boost lines for classification purposes last year and it still ran great. Albeit I wasn't holding as rock solid of boost to redline as before with the MBC, but I was very happy with the power output.


What if you then ran a 100% stock exhaust with that same tune? Would the boost be all screwy low? I ask because I slapped on the stock exhaust for the winter and got it out today and after the normal spike when the boost hits, it's immediately falling to about 15psi in 4th and like 11-13psi in 5th - albeit I'm not taking it to redline on the streets but this is what I'm seeing.

Does this make sense with the stock restrictive exhaust back on or is there another issue to chase down? All my boost lines and intercooler hoses are tight.

 

Boost will be lower when running the stock TBE as its not as free flowing.

Also, I recommend gettin another tune.

 

^^. Yeah, that must just be the case.

Logically it makes sense that since the stock exhaust is much more restrictive that it'll choke things down. Especially being my tune was for a 3" TBE.

You're right - to optimize I should get an updated tune but it's not worth the hassle. I was only using this as a backup plan to be legal for a TT event with some leftover 2009 tires anyways so not a setup I would use again.

I'm pretty sure I'm just going to put my 3" TBE back on. Otherwise I'd be planning on changing that exhaust at the track probably late Saturday afternoon/evening and that's not a fun 'planned' modification to do away from the comfort of one's garage!