Dunut Racing Heads are aewsome. I have the low profile 1 and like it alot I think its 1-2 fins lower. Fins I have seen break on stockers is when the body hole for the head doesnt have enough clearance and hits a fin constantly and 1 will break. I have never seen a top fin break. I think the new line has some cooling holes which is cool and makes it alittle lighter. MattyB I see no need for a pinch at 2 gallons. My PTM 5 port is coming up on 4 gallons and is still tight, I say I will get at least 4 more out of it. I at 2 gallons did TKO's rod pin and clips. My Powerhouse 3 port I will not be changing the rod at 2 gallons probably 4. I heated it every time I fired it and it only got stuck once and its broke in now. I will check the rod but I know it wont need 1 as early as the 5 or 7 ports. I want to put 1 of them 100% ceramic bearings in the rear of my 3 port when I can find 1. If it aint $50 LOL.