A recent customer received a 1998 K1500 pickup with a RamJet 350 crate engine and MEFI4 controller. Here are the before/after (MEFI4/24x) results of the (SuperFlow) dyno runs.
Now to be fair, the MEFI4 could have been recalibrated. But this is what GM gives you (in blue) with the RamJet 350 crate engine.