Care to explain? Why would it not run through those load cells to get to its boost target? I'm not saying that its going to be optimized at that boost level, but it shouldn't cause issues if the tune is in check.

At 25psi it should already be at its target AFR and the timing should already be correct, if not you would have detonation issues leading up to its target boost. Lowering the boost isn't going to hit untuned cells if its already tuned above the given boost level.

OP: The bottom line is, contact your tuner and verify everything. Everyone has their own opinions on what's right and wrong...but its your car not ours.

 

Agreed, but the warning was simply, if you don't know how it was tuned then you should be cautious.

 

I mean, im not gonna sit here and give you a lesson in tuning. If your interested go do some reading in the ecuflash section.

 

I don't expect you to, just curious as to your reasoning. But that's fine, carry on.

 

Yah sorry that came off pretty rude. Just been one of those days. To try and really summarize, altering the peak boost effects the entire boost curve not just the peak. So lets say you are going to hit 25psi peak and run 20psi to redline if you where to reduce that peak to say 20 you might only get 17psi at redline. The entire boost curve shifts to different cells. So you have to do enough runs at different PSI to really cover the spectrum of load cells you might hit. If the tuner does not do enough runs, and over interpolates, you could end up in a situation where it could be problematic. Now if the tuner is reputable then all is good, but since that was an unknown, it did seem worth noting.

 

Ya we all have those days from time to time. I do see what you're saying though, that's good to know and I appreciate the response.

 

Biggiesacks posts are all correct in my experience

 

Haha well I don't think I would go that far, but I appreciate the vote of confidence . Thanks though, your post just made my day.

 

Depending on how the speed density tune is setup, 25psi is probably around 240-270 load on the fuel table. Now, at 6k rpm on the high boost 41psi tune, it will never hit that load cell. Even if you lift at 6k and get back on, 25psi is on the "whip" of the turbo's boost curve, so boost is not at 25psi for any significant amount of time. Now, you lower boost at 25psi is peak and it holds it to redline, you're seeing that load cell. Most tuners tune so that lowering boost is fine. My car for example I can run anything from wastegate pressure to the 32psi final boost we tuned it on and timing and fueling will be good. Some tuners don't tune like though. So its best to ask.