solid 14's wont be a problem. im runnin 14's in an ecsb 5.3 mods in sig. your plannin more mods than i have... good luck and have fun with it. and on the exhaust, if you like loud and dont mind realy bad drone inside of the cab, look into cutouts. im sure your used to drone inside of the cab being a flowmaster fan. otherwise dynomax or magnaflow.