exhaust smog outlet plug size

I don't have a welder. And, I don't want to mess up my heads, I'm pretty good with a mig in industrial applications, have several hundred hours welding angle iron, galv and mild steel, but these are my babies, you know? I want them perfect...
Hey, have you ever noticed how optimistic camquest is? I punched in my combo with the cam whose grind is closest to mine, it came up with some rediculous numbers, if I get within 50 hp of that figure I'll boot scoot all the way to Santa Clara, I swear! And when I punch the nitrous into the equation it gets even better... 1000+ lb.s at 1000 rpm? HAHAHAHAHA! out of a 318? you gotta be kidding me... my system don't kick on till 3400 rpm anyway.