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

The grid screen is to keep chunks from damaging the MAF and a mechanically failed MAF from entering the engine. I doubt that much air flow is lost and you probably have other restrictions in the system to get rid of. Dig around on the Bosch web site, I've seen flow charts for an assortment of MAFs.

Also, the inlet side grid would tend to straighten out air flow so the MAF sensor element gets smooth air. Remember, most MAF units sample just a portion of total air flow and assume the rest based on MAF housing diameter.

Thanks for your comments

I guess a pieces of a broken MAF getting sucked into the engine could be more damaging and time consuming to get right again than leaving the grid screens on the intake side of the MAF. I'll leave them in