With holiday sales coming up, I'm trying to decide on what exactly I want to get to upgrade the exhaust on my '68.
The engine is a 383 with a Weiand 142 making 5-6 psi of boost. (Cam specs here: 12-560-4 - Nitrous HP
) On the engine dyno without all the accessories and open dyno headers, it made 560 hp and 585 tq. Back in the car with the 1.5" primary shorty headers and 2.5" exhaust with no crossover (and all the accessories) power is down pretty significantly and I'd like to get some of it back.
From my research, my engine's power output is right above the point where it's recommended to upgrade to 3" tubes, but not by much. From watching all the Engine Masters dyno tests, it looks like I should pick up somewhere between 30-45 hp by swapping to 1.75" long tube headers, 3" exhaust with x-pipe, and free flowing mufflers from the basic small system I have now. Sounding mean at WOT is great but I want it to be a pleasant cruiser at 1500-2600 RPM as well. The car has stock suspension. Only things non-stock on the underside are subframe connectors and the 700R4 crossmember. The connectors sometimes drag when going over a dip in the road at speed and I'd rather not add more things that will drag. Probably need stiffer suspension at some point..
My plan so far is:
Hooker headers because they're the new design that's meant to fit cleanly around all the obstacles like the steering box without having to hammer on them and already has a spot for my wideband sensor.
3" exhaust system since it's a good price, stainless, has an X-pipe, and I've read several good reviews of those mufflers.
Is that a good plan? What would you do differently? Think for my car it's worth the time, money, and effort? Better to just do the header swap and a 3 to 2.5 reducer somewhere along the way? I don't see any 1.75" headers with 2.5" collectors for a 1st gen. What else do I need to consider?