I was hitting 13 psi on a base 991.2 and since I’ve upgraded the headers, sport cats, exhaust and BMC air filter I can only get it the boost to hit 12psi.

Is this normal for the ecu to adjust boost for reducing the restrictions? Shouldn’t it still hit 13psi.

 

Anything that alters or adjusts the factory system I would think may have effects like this. The factory tune has to account for all sorts of variables, and your modifications have affected those variables.

I'm only chiming in because I'm sleep-deprived and no one else has yet, but there are many folks on these boards that could tell you exactly what's going on; but my guess is this falls along the guidelines of why you should generally apply some sort of "off the shelf" or custom tune whenever you modify anything that affects the normal "respiration" of the car. Especially boosted cars. My guess is that you're probably not hurting anything, but the factory ECU is probably adjusting things according to the different metrics recorded after the mods. Someone smarter will weigh in here soon, I'm sure.

Does the car feel noticeably different after the mods? I'd imagine even with slightly lower boost pressure there's probably still noticeably more power?

 

yes the car feels like it has more of a kick to it now than before. It definitely is making the same or slightly more power than before with 1 psi less. Not only this but I can definitely feel a much bigger difference in responsiveness. The turbos seem to spool faster and the sound is just incredible now.

A tune is definitely the next mod. Just deciding if I should upgrade the turbos at the same time.

 

The ecu is probably adjusting boost as it’s hitting the torque target based on your new mods (which is a good thing). You would more than likely have the same thing happen it was stock and drove the car in cooler weather. A tune will take care of that-no issues. I would say tune first on base turbos and then decide if you want to upgrade.

 

When you modified your intake and exhaust track you increased the volumetric efficiency of the engine. Since the intake and exhaust is less restrictive you aren’t backed up with the back pressure and now that 1 psi is going into your motor instead of staying backed up in your intake. This is/can be a normal situation… (as long as its not a boost leak with under-boost errors lol)

 

It sounds counter intuitive, but this is a good thing. It means you're engine's VE has improved, as has the efficiency of the turbocharger. The ECU tries to limit load (power), which is why you're feel faster on lower boost, because you are. Add a Pro-Tune and you'll get that boost back (and then some), with even more power

 

Thanks for the feedback everyone! I’m glad that adding these mods made the car breath easier and once tuned it will make a lot more power. Not sure why APR says there is no gains with these mods. Still deciding on which tune I’ll go with, there just isn’t a clear winner.

An APR tune will just be a generic tune and not take my added mods into consideration but a Cobb pro tune will, so a lot to consider.

I’ll be posting video clips of the Vektor headers/sport cats, Soul exhaust and BMC air filter on a non PSE car. Stay tuned.

 

You're not the only one who shares that thought. We've seen many plots from, all over the world, showing the contrary.

Anyone who buys/uses our products is more than welcome to see what they are getting for their dollar on our dyno.

 

I can see why people believe this to be true as I’ve felt the same on my butt dyno. I’ll be getting a tune soon, just doing my research on which route I wanna go. I’ll most likely do a dyno afterwards just to see the power gains.