E-street vs Promaxx vs 440 Source

Tbro said

318willrun, your inbox is full. Sidewinder and promaxx are the same casting. Both are finished in the United States. Sidewinder is made to order. $895.00 is bare with valves. I believe it is $200.00 more complete depending on your choice of springs.

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yes, the chinese heads are all off the same castings - Promaxx, Sidewinder, 440source. The major difference is the valve job and quality of work that goes into the casting. As for QA of the Sidewinders, I do not know. They could be very good. But, Sidewinders flow about 235 cfm @ .400 lift, the Promaxx 254 @ 400 lift. I believe Promaxx bowl-blends and all heads have 5 angle valve job.