I would ask the opinion - to do or not do a porting of the head for Evo 9.

The target is 500hp (not whp) and fast spool.

2.0L, Mahle pistons, Eagle rods, OEM crankshaft, OEM bearings, fluidampr.

For the head i plan few options:

1. +1mm intake valves, +1mm exhaust valves, guides, OEM rockers and lifters, Kelford 272 cams MIVEC, porting?

2. +0,5 intake valves, +1mm exhaust valves, guides, OEM rockers and lifters, Kelford 272 cams MIVEC, porting?

3. Stock size intake valves, stock size exhaust valves, guides, OEM rockers and lifters, Kelford 272 cams MIVEC, porting?

The turbo will be BorgWarner EFR7163, upper mount, T4, IWG.

Please, give me your opinions about #1, #2 or #3 and porting?

The car is Evo 9, using daily / time attack.

 

You can achieve your goals without digging into the head. If it needs new guides though, then a valve job would be nice. In my experience porting gets really expensive really fast. You can get more bang for your buck elsewhere in the setup.

 

Option 3, you will lose power with bigger valves.

Unless you wanted 800+ hp id stick with a good port job including 5 angle, blending the bowels etc.

Im in the same hp range with a curt head, it has ferrea SS stock sized valves, supertech guides, supertech valve seals, kiggly springs and retainers and GSC S2...