IntakesThe stock intake manifolds on 400-inch Trans Ams are fair, but some of the later castings and those used on 455s of this period need to go, as they have secondary bores that are partially restricted. Plus, as a general rule, EGR-equipped Pontiac intakes are slightly compromised. The trouble with fitting aftermarket intakes to Trans Ams is the Shaker-it doesn't fit the hood with some manifolds. The Edelbrock Performer design is not too removed from early Pontiac castings, which are known to perform well. The old Torker was a favorite since it reportedly fit under the Shaker, but this design is dated today and no longer manufactured; the Torker II will not fit, according to Edelbrock. The Edelbrock Performer RPM is an excellent manifold, and though clearance will be an issue, there is always the option of modifying the Shaker or mounting the scoop to the hood, though purists will balk at the notion.
More info:Edelbrock; Torrance, CA310/781-2222edelbrock.com
1979Another re-skin debuted with the '79 featuring a radically redesigned nose and a simulated full-width taillight that moved the rear license plate to the bumper. The new look only served to further enamor buyers, and the Trans Am enjoyed its largest-ever sales year with nearly 120,000 produced. The 403ci Olds engine was now the standard TA powerplant for 49-state cars but was only available with an automatic. A 400 Pontiac was still offered, and it maintained its 220hp rating, but it had to be ordered with a four-speed. A 4.9L (301ci) Pontiac low-deck V-8 was a new Trans Am engine option. Bigger news was the inclusion of rear disc brakes in the WS-6 package. A 10th Anniversary Edition of the Trans Am was also offered, which mandated a 6.6L engine (either Olds or Pontiac) and included a special paint scheme-a silver base with an even bigger hood bird over metallic grey paint, stretching its wingspan over the fenders. Unique graphics, silver upholstery, and turbo-styled 15x8 wheels were also part of the deal.
ExhaustAll Pontiac V-8-equipped Trans Ams from this period used log-type exhaust manifolds, which are designed for fitment rather than flow. Adding insult to injury, '75-and-later TAs have the dreaded GM pellet-type catalytic converter, requiring all the exhaust to go through a single, very restrictive cat. From there, some TAs use a single pipe to a transverse muffler behind the axle and then two tailpipes simulating dual exhaust. The '77-and-on high-output TAs used two resonators and tailpipes aft of the cat.
Any discussions of exhaust improvement inevitably involve removing, or at least replacing, the catalytic converter. Complete removal is, of course, illegal for road-going cars, and while replacement is OK, check your state's regulations on such things before proceeding. High-flow replacement cats are available from Car Sound, Hedman, and Random Technologies. That said, the simplest improvement, and one that was very common when these cars were new, is to have a muffler shop make true dual exhaust from the manifolds back. This alone was reportedly good for about 25 hp; adding full-length tube headers helps even more. Headers are available from the traditional sources like Hooker, Hedman, and others, but note that entry-level designs for Pontiac V-8 often use a single center tube for the siamesed exhaust ports. Hedman now offers a set of shortie headers for Pontiac, which use four tubes per side with stepped diameters for increased scavenging. An alternative to tube headers is reproduction Ram Air cast-iron exhaust manifolds, replicating the factory pieces found on earlier high-output Pontiacs. The repros are even available with larger outlets to further enhance flow. Try Ram Air Restoration.