From OE shop manual on a 2000 SATURN, 3.0L V6(should be close to your's) In neutral at 4,000 RPM's exh. backpressure should be no more than 5.0kPa or 0.725 PSIG. Driving test, perform short WOT bursts and max backpressure should not exceed 7.25 PSIG or 50kPa. ... Login to read more.