I ran modern cylinder head ported SR's on my super street demon. Due to a cracking issue I replaced them with -1 325's that I got from Dwayne. I chose to go that route because I am more worried in super street about a car that works well on the throttle stop and not one that runs ultimate et. I chose the smaller heads to keep the velocity in the port up when using the stop. The change between the two heads? Exact same et picked up 1 mph. Exactly what Dwayne told me would happen. Unless you are changing everything stick with what you have!!!