I am working on improving the breathing of the M113 engine in my C43. On the intake side I have installed a modified and enlarged air-box. This has given an nice 10hp increase which is dyno proven. I am now working on flowing the elbow between the MAF and throttle body. Regarding the exhaust, I have removed the secondary cats and central resonator.

Does and don'ts:
The MAF body has a double grill at the intake side (plastic and metal mesh). Do these screens serve a purpose apart from trapping UFOs which would have gotten through the air filters, or possible act as intake noise reduction? Should I leave them in or can they be removed?

Any comments appreciated