Any dyno can certify what ever it likes @ the end of the day. I see sheets from all over the world from all types and most of them count for shit in my books,
especially when you see what kind of "factors" people slap on to estimate the engine power.
Best Reference you can have is reality.
It's commonly available to almost anyone hundreds of cars (legitimate ones) from OEM sports car makers and you can find at least a dozen well known cars in your class all of which have been tested on proper electronic scales before the test, along with the OEM engine dyno rating and low and behold some "500rwhp" 300kg less Mazda's with hektik power bands still can match the figures of much less specified cars running normal manual syncromesh H pattern shift conventional gearboxes
Most if not all the figures you see from performance shops are BS, most of the engine "enhancements" especially to do with porting are a liability rather than any type of asset, making the cars louder, and much more peaky as well, all for the sake of making the same power on 1 or 2 psi less peak boost and 600rpm higher engine speed............ problem they all forget is you loose out so much mid range and upper end power before your normal red line of 8k. A stock ported 13B-REW even when fitted with a full catalyst exhaust will make usable power to 8k rpm, unlike its ported cousins it will make a shit load more power in the mid range and upper revs especially 5k to 6k rpm (where you spend a bulk of your time).
It's a great question, one lots don't really give much thought or proper on road/track analysis.