Every 6 months a new set of these Defi knock offs pops up. Every kind we’ve been brought was totally useless garbage. They read totally wrong AND inconsistant making having them worse than not having them at all. They require hardwiring from the gauges to the sending units instead of being plug and play so in the end people spend more on those than Defis because of install time. Then the gauges generally break in a couple months. One guy even had the oil pressure sending unit internally fail where the wires came out of it dumping tons of oil out and leaving him on the side of the road. Why anyone buys this crap is beyond me. You don’t cheap out where it counts.
Defi boost gauges are not off. We’ve installed dozens of them and never had an issue. I always watch the MAP sensor vs. the gauge when I tune the cars after the install is done.