Why would you need a -4an feed line when most people with MP's are running -3an with a restrictor inline? At least that's what it seems like. I would think that a -3an without a restrictior and a -10an drain would be more than enough, with a restrictor possibly being needed.

 

I am running a mp76 with a -4 feed, and -10 return. 10k miles with no problems.