Exhaust System Replacement
Removing the gearbox (to replace the clutch) and the rear-end of the Red Rocket in November 2023 required the removal of the exhaust pipes and mufflers. The exhaust was never going to come off easily, the pipes looked like they could have been original — they certainly had all the correct bends and bumps just like factory. Cutting them off was going to be the only way.
I had anticipated this back in 2022 when the car first developed a clutch noise. I knew that no matter what the problem was, the gearbox was coming out. I ordered a new exhaust from Corvette Central in the USA and had it shipped directly to SR Performance in late 2022. It was November 2023 before the car was finally checked in for the driveline makeover.
The 2½ inch exhaust system included everything from the manifold outlet to the exhaust tips including Magnaflow stainless-steel mufflers with factory-correct mounting brackets. The factory-correct mounting brackets allow precise adjustment of the exhaust tip position in the valance openings. All mounting hardware was also replaced, however the U-clamps that are visible from the rear of the car (shown in the video below) looked terrible, so I replaced them with stainless-steel Accuseal clamps (which look much neater). The overall fit of the Corvette Central exhaust was close to perfect.
Given that the Magnaflow muffler is a straight-through design (with no baffles) I was expecting the exhaust to be louder than before, but it's actually quieter and more refined.
To provide maximum ground clearance, the exhaust on the Corvette runs through the gearbox crossmember. When the new exhaust was fitted the clearance on the left side was very tight, and it was rattling a little when driving. SR Performance tweaked the exhaust on the left side to create more clearance, this solved the rattling issue.
Magnaflow mufflers from Corvette Central have 2½ inch inlets and 2 inch outlets (just like original). They feature factory-correct mounting brackets that allow precise adjustment of the exhaust tip position in the valance openings. Note the exhaust clamps in the image on the right, these are stainless-steel Accuseal clamps (which look much neater than the original U clamps).
Magnaflow mufflers from Corvette Central have 2½ inch inlets and 2 inch outlets (just like original). They feature factory-correct mounting brackets that allow precise adjustment of the exhaust tip position in the valance openings. Note the exhaust clamps in the image on the right, these are stainless-steel Accuseal clamps (which look much neater than the original U clamps).
1963-1965 Corvette exhaust manifolds could have either 2 or 2½-inch outlet size, with all high-performance small blocks (like the L-79 in the Red Rocket) using the 2½-inch manifold connected to 2½-inch exhaust pipes.
After 1965 all small block engines had 2 inch manifolds, although the higher horsepower engines continued to have 2½-inch pipes, which had a smaller 2-inch connection to the manifold. Big block engines had 2½-inch manifolds and pipes.
From 1963-1967 mufflers were either standard or the optional N11 off-road mufflers which had one less baffle inside for less restriction and a more aggressive sound.
Regardless of the pipe size or engine horsepower, muffler outlets are always 2 inches.
The factory offered an optional N14 side exhaust from 1965-1967 with 2-inch or 2½-inch inlet pipes with aluminium covers.
The new exhaust fitted to the Red Rocket in late 2023 uses mufflers from Magnaflow. Magnaflow mufflers employ a straight-through design (with no baffles) that is packed with stainless steel wool. A perforated pipe of the same diameter as the inlet and outlet runs straight through the muffler case unimpeded, and the stainless-steel wool surrounding the perforations soaks up the annoying frequencies like a sponge, turning the kinetic energy into heat, while passing the flow straight through the muffler.
This design does a really good job of absorbing acoustic energy across a wide band of frequencies — especially midrange and upper-midrange frequencies. This type of acoustic dampening takes the edge off the sound while preserving the lower frequencies — the "rumble." From a flow perspective, Magnaflow mufflers are hard to beat (a straight pipe or a bullet muffler would be a good flow analogue) and the Magnaflow sound is preferred by many.
