Except for a JDM MR valve, my '05 Evo RS is bone stock. I'm planning to eventually go with an EcuTek flash, drop-in air filter and an axle-back exhaust. It's going to be a little while until I have the money for all that though, but I really wanna do something right now to eliminate that annoying boost taper at 5K RPM's.

I'm looking into a Hallman MBC but I have a few questions and concerns. Don't worry: none of my questions are warranty related.

1. What boost level should I set for a stock '05 on 91 octane?
2. Should I expect the engine to throw a CEL?
3. Is it neccesary (or just overcautious) to install a Walbro 255 at the same time?

I've also noticed that there are 2 different ways to hook up a boost controller on the Evo: a.) the BOV bypass method or b.) connecting it to the wastegate and turbo nipple.

What are the advantages/disadvantages of each setup?

 

https://www.evolutionm.net/forums/sh...&highlight=mbc

 

installed one of these bad boys last week. I set mine 20 psi no problem at all. No CEL ...No walboro pump installed yet.. the BOV bypass method is what i did, most ppl say this is the best b/c you get faster spools....I notice a big diff after the install over stock....

 

Do you have an '05 Evo? If so what does boost spike to before settling to 20psi? Also are you running 91 octane?

 

Oh no I have an 03...After install when i had the knob turn all the way to the left i was only boostin up to 11 psi i had to keep turning it to get to 20psi.

 

1) 20psi
2) No, why? Make sure you keep the BCS plugged in.
3) No, not at all.
4) I use the turbo nipple, because that controls boost at the source instead of downstream way after the pressure has gone through a myriad of pipes and hoses, but both methods work fine.

 

hey guys today i switched the harder spring in my hallman mbc and adjusted the psi, took me like ten times to get out of my car and turn that knob little by little, cuz i didn't wanna over do it right. my cousin when on the ride with me too but long story short, we got up to 22 psi on 91 octane!!! he drove it and i sat in the passenger, it pulled all the way from 3k to 7k with endless power. love it!! of course we only did that for few pulls, then i turn it back down a little bit...1st gear and 2nd gear 19psi to red, 3rd gear 20psi to red, 4th gear 21 psi (didn't have a chance to pull to the red on 4th gear)
i guess mbc is like that, can't adjust to my own preference unlike electronic boost controller? so for now, i'll leave it like that, when it comes to auto x or track, then i'll kick it up a knotch with race gas i guess.
and for that 22psi, it shot up to 22psi then bounce back to around 20 psi, didn't stay there for long...it's awesome, nice upgrades guys

 

First of all, yes...do the Hallman at 20psi.

Other than the pros/cons in this thread...

https://www.evolutionm.net/forums/sh...&highlight=mbc

...there is one more reason I choose to use the intake manifold as a boost source. What matters to me is the boost pressure level that enters the engine, not the boost at the turbo piping. This is the same reason I did not connect my boost gauge to the turbo nipple.

I want to measure boost that is entering the engine as accurately as possible. Another example...would I connect the pressure input of the fuel pressure regulator to the turbo nipple? I wouldn't personally...but of course these are just my opinions...