hum, I remember that also, its just I have something I want to say is spark-blowout at almost exactly 250kpa. I cant really describe it but it sounds like a "POP POP POP" like a launch-control would sound, and its not redlined or anything.
I have a 400kpa map sensor, so that isnt a problem.
Volvo 242 GLT
t3/t4, RS-500 Intercooler, 46# CFI injectors, MS-2