Bit unfair that. If you get any stage 1 kit on a standard compression motor & hold it full throttle down a German autobahn for 20 minutes you can kiss goodbye to your pistons at 6 or 7 psi boost. Its a matter of simple science with excessive heat built in the chambers runnning unleaded petrol on stock injectors. The fact most stage 1's boost creep beyond that because they either use internal gates or their external gate tube fabrication is ****; means they have even less chance. Some kits dont even supply the ability for a safe air fuel ratio due to their bad fuel regulator & pump combo's.
The fact a supplier or tuner has said dont do X or Y means there is a limit with the tune of whatever kit it is. There is a limit with every kit on unmodified motors, to pretend otherwise is unwise. There are enough people out there with broken wallets n motors without adding to it.