Limiting factor to what? What is your performance goal.
You need to look at your whole car. Not just the motor.
That's what I mean by combo. I don,t buy the newest valve covers on the market just because I have the old ones off.
It has not been proven yet that the trick flow totally out performs
The Edelbrock has it? Just sayin. He'll I'm gonna run the old W2.
Sure there's some heads that beat them now, but at what cost. Law of diminishing returns imho