hey guys

i have a built 2.0 evo 8 with a gt35r kit. i have a greddy type rs bov that recircs back into a 4 inch dejon tool intake.

i used to have aem ems and wen i ran no maf and 100% atmospheric BOV i didnt really have compression surge well atleast not enough to hear it.

now that i switched back to stock ecu and stock maf with a greddy type rs i hear it so much more.

what are some main reasons that cause compression surge?? in between shifts it does it and when just cruising.

also i have the greddy type rs turned to pretty hard. cranked alot could that be it?
thanks for the help