Hey guys,

I'm looking to do a mild head shave with a BP6D. Shooting for 160-170whp. Major parts list is the following.

-Squaretop
-Maruha 264 degree intake VVT cam
-Maruha 264 degree exhaust cam
-Supertech light doubles/titanium retainers
-SUBs
-E85
-SuperMiata damper
-Boundary oil pump

Anyway, the question is, do I stick with stock valves or go with supertech +0.6mm back/undercut? Is the hp/$ there? I've been searching for days but can't find any information or results on these. Another option would be going back/undercut on the intake side only. I am avoiding going oversize as it doesn't seem to be a great payout for the headwork involved and my power goal. Any opinions?

 

searched again, found my old thread. opinions?

 

+1mm intake and stock exhaust size here, both ST.

Some will argue that +1 or even +2mm exh will help. My builder did not see the need for more flow there.

 

I'm running +1 valves all around. The +2 might need some massaging of the valve reliefs depending on what pistons (CR) you're using.

 

+1 valves increase flow at all lifts. No reason not to other than budget. +1/+2 combo balances head flow, particularly on heads with no significant porting.
+2 valves usually require larger valve reliefs on piston crowns. Industry standard for aftermarket pistons is to include reliefs only for +1 valves.