I just noticed this to. I hitting 1.4 bar or (20.3psi) with a Old school greddy profec b EBC on a 60mm Apexi boost gauge. It's fine untill about 5500-6000 rpms then it falls to about 1.2-1.3bar or (17.4psi-18.9psi). I want my extra 10hp-20hp back for the last 1,500rpms.

 

Im getting the same thing, but I think I have a small boost leak on my lower ic pipe.

 

same here.
1st and 2nd gear: 1.3bar taper to 1.1bar
4th and 5thgear: 1.3bar all the way

stock and Forge BOV give same result.

 

so, could this be a leak in the lower ic ?
haven't checked that.

 

two diff boost gauges, both read 22 psi to 7200 rpm's stock turbo, with an hks evc.. i havnt seen a thread yet about people having boost hold probs with an electric boost cont.. and only get 1 psi of spike at 2800 rpms.. so thats 23 psi in first gear, and holds there till rev limit..

 

That's how my 03 used to be, 20 psi all the way to redline in any gear. But now I have a upgraded FMIC on the 05 so I'm wondering if the turboXS has some pressure drop.

 

Well, I have more updated information. I have a buschur 3" Tb exhaust, Hallman MBC, and RMR intake. I am NOT tuned. I have tested my OEM DV, it works fine. I have checked all vaccum lines for boost leaks, they are all fine. I have taken off my front bumper and tightened every single hose clampe on the FMIC piping starting from the turbo to the TB. I also tested my little brothers MBC that he has on his WRX to see if mine was messed up. Guess what? I still taper. This leads me to believe that

1. Evos taper and its guage in-accuracy that leads one to believe that they don't taper
2. I need to adjust my wastegate arm, still haven't seen much info on this.

Other than this, I am at a loss. Maybe my turbo is just a wimp and can't keep up. Maybe tuning will help me hold the psi somehow(don't know how).

 

i never had that problem with my perrin mbc or old school profec b ebc.
Butt! i had a autometer gauge which really was never that accurate beucase 1 its alittle off to begin with.

everyone with a boost controller and a boost gauge should post a comment.

 

Same here. It doesn't suck for me actually. I'm glad it can hold it for that long!

-M

 

Mine holds @20 all the way to 8300...It even starts to float a hair above 20 as the rpms clime... I too use the HMBC... ive hooked the BC directlly to the intake manny... that line on top of the v cover does abolutly nothing.. so its just sitting there.

 

I use an auto meter procomp ultralite.. and ive never had a prob with it... Before the cams vac was about -20 and with the cams its now -15.... but My Psi did drop almost 1psi when i put on the Big FMIC... had to adjust it .. and now its fine 20 all day long.. no spiking and no fading ..

 

The oem DV only works to 19psi before it leaks..... its plastic.. just replace it and you wont have any drop... A 1g holds 25psi...and there cheap

 

My Mods are in my sig. Right now I have a Defi D Boost guage with Perrin MBC regulating my boost. It spikes to 20-21 PSI and by redline it tapers to about 16-17 PSI. I have the Hallman Pro MBC that I haven't installed yet and probably won't get to do it until Thursday, I'm hoping this is the solution to my boost drop because I can't figure out anything else. I have checked all hoses so I'm hoping the Hallman cures the taper. I'll keep you posted.

BTW, I have a friend that has a Apexi boost guage with an EBC and he holds 20PSI all the way to redline...

 

I just replaced my mbc (turbosmart) with a greddy spec s and I don't have any large problems with dropoff. I think it slightly drops by redline but it doesn't drop the 3-4 psi it did with my mbc. I also have an autometer procomp. Could be the boost controller. The spec s works great!