There's some debate about whether the sensors are really necessary, and whether they're really "3 bar" sensors vs 2.8 or whatever.
The GMPP tune kicks it up to about 24 psi, which is (roughly)~38 absolute. (This isn't entirely accurate as there's an offset and a scale, just like converting between Celsius and Fahrenheit, but it's close enough for the moment.)
That's roughly 2.6 bar. I'm not sure what the stock MAP sensors do when they get close to their limit, but typically sensors don't provide the most reliable data in that condition. In order for the ECM to correctly manage all the little twiddling bits, it needs an accurate boost measurement - which isn't always possible with the stock sensors.
For fun, you could open up the GMPP tune, set the MAP offset and scale to match the stock sensors, and see what happens. I'd guess that you'd just get a boost reduction or fuel cut a little earlier than with the 3 bar MAPs. (It COULD just let you get as much boost as the turbo can generate since you never really hit the ceiling, but fuel delivery would be an issue and Very Bad Things might happen. I'll let someone else try it.)
Trifecta's budget tune - correct me someone if I am incorrect - can work without the 3 bar sensors. I'm guessing they're just really careful. If you want to run something crazy like 30psi, you'd need sensors that can go that high, and over.
Blue-ish 2006 2.4, Werks stage 1 turbo, Borla cat-back, DDM braces, Spec aluminum flywheel, Spec stage 2 clutch, Werks aluminum radiator, some gauges, RKSport hood, Morimoto FX-Rs, GReddy Profec, Norm's fenders
'07 GXP, RPM Stage 2, Solocatless downpipe, TCE Wilwood 6 piston front brakes, 4-piston rears , Stainless brake lines, slotted/drilled rotors, BC Racing BR coilovers, Performance Autowerks intercooler, DDMWorks CAI, charge pipes and braces
Last edited by raygun; 01-18-2019 at 02:58 PM.