A few mods... Typhoon / Popcharger intake, plenum and throttle body spacers, fujitsubo exhaust manifolds, kinitex hi flows, 5zignen y-pipe and zorst... running 291 at the moment with the unichip on a 276 model (but I think I was running about 249 on the first dyno stock...)
It depends on your 296 if it is running at that and if your tuner knows the Zed!!! could be 20bhp, could be 5, could be 40!! you can get the parts from Envy performance, OM gaz walker or Chilli red on here for prices...