Hi Everyone,

I recently had my 05 Evo 8 serviced by a local Mitsu dealer and along with the usual checks they seems to have replaced my vacuum lines and "defaulted" to boost to 10-12 psi (which from what I know is the wastegate limit, if one does not have the correct vac lines with restrictor pills)

When I addressed this issue the mechanic informed me that on my model the stock boost should be between 7-12 psi and starting around 2006 is when the Evo's boost was bumped up to ~19 psi. Honestly to me it seems that the machanic was making this up, but he referenced some kind of service manual and it seemed unprofessional to start arguing with him so I too his word for it.

Can anyone provide some insight to this, should my boost really be ~12psi? (I'm ok with being wrong, just everywhere I've read stated that the boost peaks at 19-20psi)

Best regards,

 

Stock boost is about 19psi, tapering to 12 in the upper rpm range on evos from 2003-2006. Get a new mechanic or do the work yourself next time

There should be a line connecting the turbo outlet pipe with the WGA with a T on it. The T runs to the BCS and then is bled off to the intake pipe. The hoses around that T have a boost pill in them somewhere to elevate boost above the factory rated WGA cracking pressure of 12psi by bleeding off excess air through the BCS.

However, if you have some mods and no MBC, you might see lower boost than this, because the stock ecu controlled boost is load based. You will see the same load at less boost with modifications that make your car breathe easier. Best bet, kiss your warranty goodbye and visit your local tuner (GST Motorsports for example). A full exhaust, MBC, and tune and you will never need to talk to someone who doesn't know (fully) what they're talking about ever again

 

Lol yeah definitely better off doing the work myself :-p ... I always assume that certified mechanics would know more than me, but I'm proven wrong time and again (you think I would learn lol)

I'm familiar with the vac lines and the basic design so installing the correct lines (with pills) will not be a problem although at this point I might as well go with a MBC. The only thing with the MBC is that I'll probably have to spend some time with my laptop and EvoScan to correctly measure load (I don't want to eyeball boost psi off my gauge)