I want to swap my Nismo R-Tune cams for a set of tomei 268 cams. I know I will need stiffer valve springs, ti retainers, and UTEC for tuning. I'll also have the motor clayed just to make sure the valves do not hit the pistons (probably not necessary but I am planning on having the heads milled also). Is there anything else I will need (I searched and I could not find any reviews on the timeo 268's)?
Also, there is the plenum choice. I'm having a little difficulty choosing the right plenum. Should I do for the 5/16" spacer, the MREV2, or the Crawford plenum? In NA apps what matters most, having more surface area (IE: 5/16" spacer) or having equalized airflow to all of the cylinders (Crawford)? Thanks.

 

I wouldn't worry about claying. These don't have a enough lift or duration to create a possible problem so don't worry about that.

Do not mill the heads as well. Remember you have a timing cover on the VQ motor so that's not a great idea whatsoever. And i've also read VTC issues could arrive due to milling the heads. Not worth the trouble. If you want to increase compression get a nice set of pistons.