Ukautograss

Ok story goes got a sti v2 wagon and was keeping it standard ( how many of us started like that I hear u cry ) so replaced the headers and up pipe then the decat , put 440s in , got a apexi power fc mods to follow are fmic, td9520g , walbro, then mapped , it's running the standard ecu at the mo , that's the back ground what im asking is once the exhaust was on and injectors changed I took it for a spin see what it sounded like and don't get me wrong I know it's not mapped so I wasn't being stupid with it I blipped it in 3rd gear and it hit full boost intact went past and hit 1.1 bar I wasn't expecting it to of it caught me out as it spooled a lot quicker to be fair , but what I noticed was it didn't pull and it started to miss I think , it returned to normal as soon as I shut off , as soon as the other mods are done jgm will be mapping it I'm just worried that he will turn up and just say something ain't right and not be able to do it , the ecu that's in it is chipped for yellows anyways so would the exhaust being changed do that kind of thing , make it over boost and feel like a miss fire ?.

Ukautograss

Also been told I don't have to run the lambda sensors on a power fc as mine are welded into the headers and down pipe is this true ?