Exhaust Cut Out-Higher Boost Level

[tcgn]

I ran a hose to turbo to wastegate(tuner style)and WOT in 3rd gear 3 times.Rock solid 16 psi.Then I open up the exhaust cutout and WOT boost shot up to 23/24 and my knock detector went crazy amd I let off throttle.I WOT the 2nd time and it shot up to 24# and possibly would go higher but I let off. Has anyone experience that much boost increase due to free flowing exhaust?
I just bought the DAWES DEVICE MBC.I WOT tonight just to see where my boost is at before installing the MBC.Right now,I better find and fix this boost problem first.I`m using HD actuator adjusted half of a circle to hook up the wastegate.
Any help is appreciated.Thanks
Thomas

 

[JToups386]

An open dump can generate anywhere from 1 to 3-ish psi more boost, w/ all other factors remaining the same. It depends on how restrictive the exhaust system is.

 

[tcgn]

Thanks for responding.My exhaust must be restrictive.I`m using the cat. and 2 21/2" Ultraflow mufflers(straight through design)
The catalyst converter is 2 yrs. old.The muffler shop remove my cat to install the exhaust cut out moving the cat further back for room.I look at the cat and it looked o.k. maybe it`s partial clogged?

 

[Sleeper-6]

I Know my exhaust is HORRIBLE, I opened up the dump the the other night and my boost shot from my normal 17 psi in third to 22+. It was still climbing when I let out of it.

 

[JoeNational]

Ok i still have the stock 2.25" exhaust with reg muffler and 3"THDP with the dump open in the streets like all the time, I have no cat either. my boost is set at 15psi with or without it being opened, iam going 3" ATR very soon but it seems that your boost seems to be at what it says because thats all it gets because of restriction but when you un-restrict it she spooling like crazy.

 

[tcgn]

Yesterday I remove the HD actuator and install the stock actuator
and the boost is 13# and 18# using the exhaust cut out.
Maybe opening it 75% instead of 100%