Oem and gt500's are chambered non packing mufflers. Straight through designed mufflers are ideal for flow. I'm running ORX with these race bullets in T304.
Surprisingly not bad for fairly open exhaust. Nice pick up in power over 5k rpms with my CJ setup versus the oem mufflers. I would have gone gt500 if they had not almost doubled the price on them. Bought these shipped for 270.
2014 GT Cobra Jet California Special
Auto, Oxford White, comfort pkg.