 Our GP benefited from the...  Our GP benefited from the SLP bolt-ons. From stock baseline to the Part I and Part II add-ons, we netted just over 35 peak horsepower and 15.8 lb-ft of torque at the wheels. Gas mileage improved by nearly 4 mpg. |
 Stock carbon-core wires break...  Stock carbon-core wires break down and usually show resistance levels of over 1,000 ohms per foot even when new. Performance Distributors LiveWires have a spiral-wound core preventing electronic interference and offer a resistance of only 300-350 ohms per foot. |
 Though the stock GM coils...  Though the stock GM coils are known to produce plenty of spark power, the Screamin' Demon coils are designed to produce exceptional spark power with no drop in power at higher engine rpm (5,000-up). |
 Your author and other Primedia...  Your author and other Primedia publications have seen improvements (strip and dyno testing) using Performance Distributors products. We felt smoother throttle response but didn't see an improvement on the dyno. However, the upgrade in materials and durability over stock are better reasons to use these products than a possible gain of a few horsepower. |
A game plan of efficiency and performance can go hand in hand as long as all-out power isn't the goal. For my wife's daily driven '00 Grand Prix GT, efficiency is a priority. So far (if you read Part I in the last issue) we picked up 2-3 mpg and 13 front-wheel horsepower from the SLP Performance Parts bolt-ons (1.8:1 rockers, airbox, and catalyst-back exhaust). Like most who want more of a good thing, we were confident SLP's 151/48-inch equal-length stainless steel headers with 3-inch collectors and a 3-inch flexjoint could add even more punch and thrift to our 3800.
These headers cost $749.95, can be used with supercharged or normally aspirated GPs, and are found under PN 30070. Mandrel-bent 409 stain-less steel tubing and OEM flanges are employed, and an aluminum-ceramic coating is applied inside and out for lasting luster and durability. Provisions are made for the factory EGR and oxygen sensors-the latter have their fittings located to eliminate sensor-to-body contact when the engine torques in its mounts. Neither welding nor cutting are required for a proper fit (air pump-equipped GPs will require welding of the air tube and flange, however). SLP's performance guarantee and lifetime limited warranty are also included.
A high-flow catalytic converter (SLP PN 30073, $179.95) or an off-road race pipe is required with these headers. Of course, we took the converter to keep the GP street legal. Also needed is an installation kit (PN 30071, $89.95). In the SLP catalog it claims its W-body headers, "Produce up to 25 additional horsepower, depending on application." That's a big power gain for a V6-even if it's supercharged. We wondered if our nonsupercharged six would come close to that power increase on the chassis dyno.
Ignition Upgrade
Before we made our date with SLP, we knew it couldn't hurt to replace the aging factory-installed ignition wires (date coded 8/99) and coils. Performance Distributors had just released its LiveWires (PN C9043, $89) and Screamin' Demon coils (PN 31735, $99) for the '95-up 3800 front drivers.
LiveWires feature heat-treated glass-braid sleeves that are resistant to chemical corrosion, moisture, and temperature damage, from -76 degrees F to 1,400 degrees F. A silicone jacket and insulation also keep moisture away, and swivel boots are employed to ease installation. A spiral-wound core thwarts electronic interference, and the 300-350 ohms-per-foot low resistance allows for excellent spark travel. The set is custom fit and assembled (no add-on sleeves) and each wire is numbered for foolproof installation.
Screamin' Demon coils employ a brass terminal to attach the coil wire. According to the company, the brass terminal is more conductive than a typical aluminum terminal and will resist corrosion better. Increased coil energy allows for a wider spark plug gap, which could increase power and mileage.
Though Performance Distributors ignition products have shown improved performance in previous strip and dyno testing on other makes of motors, back at SLP we ran identical numbers to our last pull on the rollers. This is possibly because, though Performance Distributors recommends increasing spark plug gap to 0.060 (due to the increase in coil power) to improve mileage and horsepower, the stock plug gap for the GP is already 0.060. Another factor is the power increase is generally found at 5,000+ rpm and our GP makes peak horsepower at just 4,790 rpm. Regardless, our intent was more to increase durability and reduce maintenance with these high-quality ignition parts.