What is the difference between the two?

 

race core is a straight through silencer. It is therefore louder but has no restriction. Restriction can be added by putting on disc, the more disc the less the restriction. The exhaust can be tuned to the engines needs with the amount of disc. Engines that are for low end power and torque will use fewer disc for better scavenging at low speeds while an all out high rpm race engine will use more disc or no disc at all. Supertrapp includes some guidlines and recomendations on the number of disc for a particular application but you will still have some trial and error to do. The quiet core has a baffle that forces the exhaust to go around it. This makes it quieter but adds restriction and back pressure. the disc are still used in the same way but once you reach ten disc you have reached the flow limits of the silencer and adding more disc will do nothing. If you are building a mild motor with a better breathing filter, jetting and a pipe for recreational and trail riding or even some for fun racing the quiet series will do very well and help keep the peace. The race core is needed if you are building an engine with high comp, cams, porting,big carb, rev limit removal,and maybe a big bore for all out power. These mods will drive the good part of the power curve up in the rpm range and require a free flowing exhaust like the reace series.

the choice is determined by the application

 

Thanks. It sounds like I am the perfect canidate for the quiet series. I hope the pipe and silencer makes as much much difference as the jet kit did.