[C5GTO]

Yes, the car has an EEC IV EFI setup, larger mass air meter, large injectors and Edelbrock EFI intake manifold. I worry about lean conditions (maybe over worry) because it ran lean before I had it dyno tuned and re-calibrated. I think the intake and heads are capable of flowing plenty of air, once the exhaust side is no longer restricted, hopefully it will all balance out. I seem to recall the dyno had the engine putting out about 300HP after re-calibration.

After doing more research on the different mufflers mentioned (and some others), I'm leaning towards the Flowmaster Slimline sidepipe mufflers. It looks like I'd need to adapt from 3" collector to 3.5" opening/outlet to turnout but that just means a couple more welds per side.

Has anyone heard or experienced anything negative about the Flowmaster muffler?

It sounds like one positive is that they will be cooler to touch with the double siding. I've had my kids and one friend get a "snake bite", that's never fun.