This is Doug Terry's 1995 Camaro Z28. We installed a custom 383ci  LT1 Stroker with AI Head & Valvetrain package, Stainless Works LT Headers and a Mufflex 4" Exhaust.  We dyno tuned the car and it only had 333 RWHP at first with a very restrictive exhaust the most was 360 RWHP. We then installed  ported MAF ends and swapped the restrictive exhaust with the Mufflex 4" exhaust and when finished it was at 426 RWHP & 411 ft/lb of torque. That will show you how very important a good exhaust and a dyno tune helps.