Smoker will be 24" x24" x48". Stainless steel welded 18 guage internal box. Roxul r15 insulated. Using 1500 watt element for heat. PID controlled. Mail box mod for smoke. Target temps of 250-275 hopefully. I plain on the mail box mod to be only air intake. My question is how big of exhaust i need. Do i need a 4" exhuast or would 1" be enough. I am sure i will have more questions, but this will get me going on the build. Thanks for input.