I installed the Hallman MBC this weekend and notices that it drops 1 "notch" on my Defi-D gauge, so from 20 to about 18.75 psi before redline in gears 2-5 and two notches in 1st Is this normal for the EVO? Would replacing the BOV with the MR help that at all? Thanks.

 

 

All lines are as snug as they can be on there, and most are zip-tied. It doesn't drop any lower than around 19 psi near redline, even if I push it to the 7500 rev limit.

 

I have the PRO-RX from Hallman and have a similar problem, towards redline I loose about 1-1.5 PSi. I double checked my connections and I'm sure I don't have a leak on the MBC lines. I'm guessing it's my BOV that leaks under load. I also read that it's normal since the car isn't really under a lot of load towards redline.

 

Yes this is normal the stock turbo naturally tapers slightly 1 -2 psi. I have yet to see any Evo keep the same boost all the way to redline with either manual or EBC. Those who have stated so then actual got their Evo on a dyno have seen that it still tapers no matter what your gauge says.
If you want a for sure answer ask Al or Shiv or David or any of the tuners who have cars on the dyno all day long.

 

I was thinking along the same lines. I'm going to use the "BOV test" in the FAQ this weekend to see, but if it is normal, it would be a waste of time.

 

Mine holds till I let off the gas.. No taper here

 

Mine does the same thing. Perfectly normal.

 

Mine tapers a bit too.

 

Probally the BOV...

 

mine doesnt taper really at all............. i have a new bov though...?

 

its normal. Mine peaks at 21 and tappers to 19.5. Its normal since evos peak even when stock. It's all good though.

 

This thread is funny some say it's normal to taper and some say no they get no taper.
What's the truth?

Does it really have to do with the BOV?

Mine tapers too by redline.

 

i think it has to do with where your boost source comes from.

 

Mine tapers as well. Do not believe everything you read, this is the internet and people post more bullshet than truth.