It all started with a visit to SLP Performance Parts. We stopped by to purchase one of the company's Ram Air hoods for hobbyist Kelly Holloway's '99 Trans Am. This non-Ram-Air F-body suffered a front-end collision (a lifted pickup backed into it), and the owner decided to ditch the damaged stock, flat hood for the better-looking twin-scoop hood. While shooting the breeze with the SLP guys, they mentioned the company's new PerformancePacs (350, 375, and 400hp). Intrigued, we decided to test the Stage 1 Pac on this stock T/A
While the dyno can show us power increases, we like to see how much lower the e.t.'s can go with popular bolt-ons, so a strip test was scheduled. The 350hp Pac is comprised of "jointly engineered induction and exhaust components," according to SLP, and consists of a FlowPac cold-air induction system, which includes the high-flow airbox lid; a cold-air induction package; a high-flow Blackwing air filter and smooth bellows; and the Loud Mouth II modular stainless exhaust.
Because the T/A is 8 years old, we added a new set of Performance Distributors LiveWires as well.
At The Strip
On our way to Raceway Park in Englishtown, New Jersey, we stopped by SLP to pick up all the boxes for the PerformancePac. Amazingly, they all fit in the back of the T/A with the rear seat down. Sharp HPP readers will remember that SLP added power and efficiency to my wife's '00 Grand Prix GT with its high-quality parts ("Six Sense," Nov. and Dec. '05 and Jan. '06), so I was looking forward to the performance improvements on this F-body.
It was March and we were blessed with cool 48 degree temps when we arrived at Raceway Park. We felt it wise to start testing with the cold-air system on this great-air day. It was inspiring to see this box-stock non-Ram-Air baby run a 13.33 at 103.36 on its baseline pass. Two minutes later, we hot-lapped it to a 13.35 at 103.22. For all testing, launch rpm was 1,200, the shift point was 6,000 with the shifter in Drive, and tire pressure was 40 psi in front and 28 psi at the rear. The result was this 80,000-mile world-class powerplant turning e.t.'s identical to automatic 3.23-equipped T/As back when they were new. With that consistency, we knew we had a great test mule.
We got to work on the cold-air induction, but at 12:30 in the afternoon, we were off to a late start. This upgrade ended up taking over three hours to install, but it turned out to be well worth the effort when we scooted down the strip to a much-improved 13.11 at 105.21. A gain of over 0.2 and nearly 2 mph is similar to picking up 20 hp. Unfortunately, we didn't have enough track-time left to test the Loud Mouth exhaust.
On our next track visit, it was a typical May day with worse weather conditions (mid-60s, higher humidity, and lower barometric pressure). Naturally, our baseline was a slower 13.24 at 104.71 with a 13.27 at 104.60 hotlap. It was to be expected with the less-than-favorable weather conditions. However, this Bird was performing with the same dead-on consistency as the first test. Now with a solid baseline, we were ready to remove the stock restrictive exhaust.
When we laid the stock and SLP plumbing side by side, the difference in the two systems was apparent. The stainless mandrel-bent pipes of the Loud Mouth II muffler don't appear to have any obvious flow restrictions, unlike the stock pipes and muffler. Once the new tubes were in place, we couldn't wait to start it up to hear the healthy tone.
We went to the line with the temp gauge just coming off the 160 degree mark, the same as the other baselines and test. Out of the hole, the LS1 felt slightly more sluggish, and it showed when the board lit up a 1.98 60-foot (0.01 slower), although the mid-range and top-end pull felt noticeably better going down the track. We were pleased when the clocks posted a 13.14 at 105.99, a full 0.1 and more than 1-mph gain over baseline. On the hot lap, we slowed to a 13.18 at 105.58.
Next up was the LiveWires ignition wires. We didn't have time to change the 80,000-mile original plugs but felt the wires could shave e.t.'s given SLP's in-house testing results. After a knuckle-busting hour, the LiveWires were installed. The motor fired right up, ran smoother, and the throttle response felt better. This kept our hopes up for more reduction in the e.t. department. When the 60-foot lights read 1.97, we knew we were on a good run. The T/A turned a 13.10 and now the trap speed was over 106. If we had been able to test all the products that cool March day, 12-second e.t.'s may have been possible.
We used a friend's bone-stock...
We used a friend's bone-stock '99 T/A (LS1, auto, 3.23) to strip-test SLP's 350hp PerformancePac. The Ram Air H.O. hood is new from SLP because the original was damaged. This is not a WS6 Ram Air car.
A big, bulky, baffled stock...
A big, bulky, baffled stock air-cleaner setup doesn't satisfy the LS1's hunger for airflow.
The stock paper-element air...
The stock paper-element air filter restricts airflow. This paper filter was new for a fair comparison.
This stock radiator-support/air-cleaner...
This stock radiator-support/air-cleaner base and the air dam underneath were removed for surgery. A jigsaw blade, sharp utility knife, or cutoff wheel works well. (Read SLP's detailed instructions before attempting to install the FlowPac cold-air induction system.
After reading SLP's instructions,...
After reading SLP's instructions, two square holes were cut in the airbox base. Not visible underneath is the plastic air dam in which a rectangular chunk was cut out. These mods make room for SLP's stainless cold-air scoop (inside and under the cut-out squares).
The stainless scoop is mounted...
The stainless scoop is mounted in the high-pressure air stream in front of the radiator. It helps jam the air through the high-flow filter into the air-hungry LS1.