A fellow GN owner mentioned that both maf screens should be present when using a Thrasher chip. I'm sure he is correct but I'd appreciate anyone else's comments on this. Thanks
You may get away with it but....the Thrasher is an open loop chip at idle and WOT. That means it is referencing a table while in open loop rather than adjusting fuel based on O2. Changing the air flow from what is expected will affect idle, but it may be possible to tune iac and fuel pressure around that, which deviates from Thrashers recommended settings. I always had the best idle with both screens present when I ran the Thrasher.