me and a friend managed to pass a 5 gas but only just, was a forged sr20, stock cams, gt3082 top mount, run of the mill highflow cat, we told tuner to keep in mind we were gonna do an emmission test and he took that into account and we passed first go basically
its not a hard test to pass, they didnt test the car on full boost so it doesnt really matter wat turbo ur running, aslong as ur tune is decent and ur cat is working you will be ok
all tests were done in nuetral on idle and also with revs raised for quite some time ( quite a dumb test but works for me )