Holy smokes! That's a lot of exhaust flow, particularly out of a 1.600!! Same with the 1.625! I can almost see the picture although it is blurry. I am not sure what I need to do to see Photobucket pictures. But I can see enough to get the idea. I used some long reach probes to measure where the water is, (not calling them the right thing, where's the coffee!) and it appears that I have all kinds of room before hitting water. I have promised myself I would build a flow bench someday. Still hasn't happened. I'm using 1-5/8" primaries right now for headers, which probably doesn't help the entire picture. But at least I can open up to what I am using.Yes you can make an exhaust port flow a lot more if there is enough material to get to the right port shape. The vast majority of mass produced CNC ported heads have a generic NA port programs. Most of the higher end porting shops offer some specific options for power adder heads. I have some 18* heads that flow almost 290cfm on the exhaust with a 1.600" valve and I have some AJPE 13* heads that flow 325cfm with a 1.625" valve. Both ports have a almost conical port profile to achieve these numbers. The 18* port exit is a rounded square shape, sorry I don't have a pic on my phone to post of that one. The pic below is the AJPE SB head, to put it in perspective the smallest header tube that can be run is 2.00" and it just barely large enough to not cover the port.