Hi all, first post, went in on a 94 Viper a couple of weeks ago with a friend [time share kinda deal] live in Pleasanton CA. cannot pass smog also have a loud afterfire in right side exhaust like a gunshot at times, between shifts unless back on throttle quickly and sometimes during steady throttle so we have decided to go back to stock headers and stock exhaust system with cat [have none now] we think it has Hennesy headers , took off side sill has one long muffler, we have been told that it has Hennesy 500 package dont know for sure as we have no paperwork from owner and even if we did still woulnt know as Hennesys work or lack of is in question according to posts on forum, called Hennesy with VIN number to see if they could help but was told all records were lost prior to 2008. The car runs really good no misses at all we are hoping the pop will go away with cats and be able to pass smog as we think its unburned fuel that is igniting in the muffler the car has about 18000 miles is in pretty good shape all around has air con thats not working needs some TLC maybe some new parts dont know yet, all I can see for sure in changes in mods is headers, muffler, intake air tubes, kn filters dont know if throttle bodies are stock or changed out spark plug wires and plugs that have the snake tongue. We hope that we are not going to stuff the motor with not enough exhaust flow by going stock if mods were made internally to engine cant see any other options at this point has anyone gone through this change back to stock any insight would be appreciated. thanks for any replies