Last time you saw this particular 305 Tuned Port Firebird, it had just gained 8 rear-wheel horsepower thanks to a Dynomax Super Turbo cat-back exhaust system (see "The Frugal Formula," November 2002). This resulted in a best quarter mile elapsed time of 14.64 at 94.54 mph. Not too bad for a 138,000-mile 1989 5-liter 5-speed, but still not that great when you consider what today's vehicles have achieved.
This month, the quest for affordable performance continues with the addition of a set of Dynomax 1 5/8-inch headers. One look at the factory exhaust manifolds and any self-respecting gearhead will go running for the parts catalog. Since the Dynomax catback system had performed so well, it only made good sense to see if they had a header system for the Firebird as well.
Part No. 87705 contains a set of emissions-legal, 1 5/8-inch Jet-Hot-coated headers, Y-pipe and a host of other necessary pieces that make the installation a complete affair. These headers are designed for 1982-1992 Camaro/Firebird models with some years requiring various modifications here and there for proper fitment. At $457, they are not quite the bargain that the cat-back system was but on the other hand, these are high-quality pieces that will last quite some time thanks to the Jet-Hot coating they have received. The headers themselves carry a 90-day warranty, and the Jet-Hot coating offers a limited lifetime deal. The non-rusting finish will be both pleasant to work around and pleasing to the eyes. The price is in the ballpark of similar products, and receiving positive results from their installation justified coughing up the coin.
Installation is not that difficult a task should you have a good relationship with your local Snap-On or MAC Tools dealer. Our northern, rust-infested 'bird required the use of such things as an offset ratchet, a torch to heat up the weatherized bolts and tools to remove broken studs and bolts, of which you'll most likey have once you begin this install.
This author enlisted the help of Danny's Pro Performance in Keyport, New Jersey to complete this odyssey. The crew there is well-versed in automotive repair as well as high-performance machines, so Blue Thunder (as we've named our '89) was in good hands. To do this job right, you'll want to devote at least two days as it requires many permanent modifications that should be planned out. This time allotment also takes into consideration things like exhaust pipe clearancing, broken bolt removal and welding.
Once the headers were in place, Blue Thunder was off to the dragstrip in search of some positive results. Unfortunately, the weather was not up for creating optimal elapsed times at Englishtown's Raceway Park. Blue Thunder's previous best of 14.64/94.54 was accomplished in considerably better air than the header follow up. According to the TAG weatherstation on hand that day, atmospheric conditions registered 200 feet above sea level.
Wednesday night's test and tune at E-town came in at 1,800 feet above sea level, which is why Blue Thunder managed a mere 14.98 at 93 mph on its first run. It did smoke a 5.0-liter Mustang though. BT's next run improved to a 14.68/93.56, which was mostly due to the author improving his 60' time to a 2.14, as opposed to the previous 2.32-second time the run before.
Not wanting to leave GMHTP readers hanging, Blue Thunder made a couple of runs on the Crazy Horse Racing Dynojet to verify exactly how the Dynomax headers performed. As you can see from the results chart, Blue Thunder picked up almost 7 horsepower and 12 lbs.-ft. of torque at the rear wheels, bringing the totals to 206.2 horsepower and 286.7 lbs.-ft. of torque. Your author hopes to have Blue Thunder back at the track soon to get a better ET, and hopefully close in on the 13-second zone. Thanks to some quality Dynomax parts, the blue 'bird is that much closer.
Our old friend, the can of penetrating solvent, was once again called to battle to remove bolts with 13 years of rust and corrosion. Spray it on, then let it sit for an hour while you kick back for a few beers. | 
An angled 3/8-inch ratchet should be considered essential for a successful header installation. | 
The factory manifolds came out easily, with the hard part consisting of drilling out the broken bolts. Remarkably, Blue Thunder only encountered one such problem. |
As mentioned earlier, the Dynomax kits are designed to fit 1982-1992 models. That being the case, Blue Thunder didn't need this tube, which is used to provide heat to carbureted engines. A cut-off tool made quick work of it. | 
Can you say flow? Visually, the Dynomax pieces would obviously flow better than the manifolds, and the dyno test proved it. The Dynomax pieces come with the AIR tubes installed, but the black fittings had to be swapped onto the new headers. | 
The Dynomax kit includes a Y-pipe, which works great if you have a single-catalyst exhaust system. Our dual setup required cutting of the Y-pipe to connect the headers to the cats. Dan Ryder cut the Y-pipe and factory cat pipe, leaving extra room until he could get the exhaust components back on the car to more closely approximate the needed lengths. |
Once the lengths were established, Dan welded the Dynomax flanges onto the factory cats, and painted the adjoining areas with a rust-inhibitive paint. | 
The new headers are so nice, the author feels compelled to do an engine detail now, but that will have to wait until later. When bolting up the driver's side header, there is no emissions equipment to work around, however the steering shaft needed to be temporarilly unbolted in order to get the header into position. We've run into this before when installing the SLP 1 3/4-inch headers on our other third-gen car, Magnum TPI. | 
Here, Dan Ryder and Rob Sisko of Danny's Pro Performance tend to the last details of the installation. This included re-routing the spark plug wires to make sure they cleared all of the header tubes. Blue Thunder recently had a new set of ACCEL wires put on, but two of them which had straight boots needed to be replaced with 90 degree pieces. |
As you can see from the graph, Blue Thunder picked up power and torque across the board. This author is getting excited as the thought of hiding from Nissan Altimas and Acura RSXs is beginning to fade from his mind. | 
It's really hard to discern anything less than a 10 horsepower gain with only a few runs under your belt. We already knew that going in, but we gave it the old college try anyway. We saw no improvement in ET, but the weather was a definite factor as conditions had deteriorated over the baseline test. We think future track testing will bear out the dyno-proven gain. | |