Adjusting the wastegate actuator rod doesn't act as a MBC, all it does is controls the onset/fade of boost. If your wastegate actuator looks like it's been tampered with, I would test it to see how much PSI it's adjusted to. Tech has a "how to" link for that.

Seriously, I have hit the end or limits of the 15G. I am four turns out, IPD ECU which kills the fuel cut off. Then that was not enough so I put in a MBC and set it to 15psi. That turbo is absolutely maxed out. You can feel there is nothing left. The car litterally peaks and hangs right at that point. The turbo cannot push any more through. At 16psi there is nothing, no improvement. At 15psi the boost pegs then sets back at 14.5psi.

What I am trying to say is go with 14psi and feel confident your at the max. Any more and you will hit fuel cut off(which is very frustrating as well as very startling). If you want anything more out of the car you will have to change the turbo and exhaust.

With supporting mods a 15G is effective all the way up to close to 18psi. Some dude dyno'd w/ a 15G, turning up the boost the whole time.

Yes with mods, I think what he is trying to do is get the most out of his car by altering the Turbo only.

Then I would not go above 13 PSI to allow for books spikes between shifts.

You decide what you want to run. Its an automatic I presume so the spike between 'shifts' really does not happen.

We can only suggest, you will have to find your happy place. Here you have two people running their volvos at 14psi and me at 15psi. Both have found their happy place without issue. Because of what I have personally seen with the limits at 15psi I would recommend Techs setting of 14psi. If for some reason you hit fuel cut off then drop it to Gilber33 recommendation of 13psi.

I think with all these recommendations you should have a good understanding of what to look for or expect as you get closer to these settings. For now, get yourself a boost gauge, install your MBC and start playing.

My mechanic made me worry a little today...he told me start saving money cuz the MBC will cost me lots of money since its an old car. Is it possible to blow out the head gasket at like 12-13 psi? My car has 207000km on it...think there's a possibility of damaging the engine since it has high mileage?
Is it necessary to have an aftermarket exhaust/intake? Would a K&N air filter be sufficient as an air intake? lol

:confused: You're not the only one running a MBC on a high mileage 850, in fact, is there such a thing as a not high mileage 850 anymore?. 12-13 psi should be completely fine. Yes an exhaust will help but that slight increase it's not necessary. There are people running 20+ PSI on the white blocks with bigger turbos, your head gasket will be fine. I'll be running about 15 PSI on a 19T with a stock motor.

Once again, your car should be fine. Yes the possibility is there of raising boost without a tune. People have bent rods on a stock motors with a MBC and a tune, it's always a possibility, even on a completely stock motor it's possible, and when you start playing with it, the chances increase.

Read THIS before you do anything.

i Finally got around to doing the stage 0, now finally bought a MBC and will be installing it soon.

Cool be sure to update us on the BIG smile after driving it!! LOL

hehehe will do

Any updates? Thanks! (looking to install one on my 850 too!)

ghosts of volvospeed past