If you're going for a N/A 306 you don't need anything more than the 165cc runner heads like the TFS TW, or the AFR 165's. Since the AFR's are way more than $1k, and the TFS TW outflow them (everywhere from what I've seen), it cuts down the options.
The Windsor heads are crap at low lifts, and from the flow data, you can see how linear their flow rate is. They also have very large runners which hurts port velocity. If you talk to the guys who run TFS heads, they have great low end, along with superior top end.
The GT40x head flow numbers I've seen haven't been all that impressive compared to AFR's or TFS's.
|