You can feel fuel cut coming before you hit it.. the options you have are either restrict the intake, or the exhaust. So put the airbox back on, that may help, or restrict your filter. Or, restrict the exhaust side, so put the cat back on, or fit a restricter ring in the exhaust. A manual or any kind of boost controller cant lower boost from what it naturally boosts too. If its boosting to .9bar on its own, setting an EBC at 0.7 wont hold it back.