1999 Porsche Boxster Aftermarket Parts: A Practical Guide for Upgrades and Maintenance

The 1999 Porsche Boxster (986) is a popular entry-level sports car that offers mid-engine handling and classic Porsche styling. As these cars age, many owners look to aftermarket parts for performance upgrades, cosmetic enhancements, or simply to keep their Boxster on the road. This guide covers the most reliable and cost-effective aftermarket parts for the 1999 Boxster, organized by system, helping you make informed decisions without overpromising results.

Engine and Performance Upgrades

Intake and Exhaust

Replacing the factory intake and exhaust is one of the most common first steps. For the 1999 Boxster (2.5L M96 engine), aftermarket cold air intakes like those from EVOMS or Fabspeed provide a modest horsepower gain (about 5-10 hp) and a more engaging sound. Expect to pay $200-$400 for an intake kit. For exhaust, cat-back systems from brands like Borla, Magnaflow, or Cargraphic offer improved flow and a deeper tone without being overly loud. Prices range from $800 to $1,500. If you want a full header-back system, prepare for $1,500-$3,000, but note that header installation is labor-intensive and may require a tune.

Engine Management and Tuning

A simple ECU tune can unlock more power from the 2.5L engine. Companies like Softronic or EPL offer flash tunes that raise redline, optimize fuel and timing, and can add 10-15 hp. Costs are around $500-$700. For more aggressive builds, standalone engine management (e.g., Motec or Haltech) is available, but these are overkill for a mostly stock car.

Cooling System

The 1999 Boxster is known for coolant pipe failures (the plastic coolant pipes at the front of the engine). Upgrading to billet aluminum coolant pipes from LN Engineering or similar is a smart preventative maintenance step. These run about $250-$400 and eliminate the risk of a sudden coolant leak. Also consider a lower temperature thermostat (e.g., 160°F) for track use, but note that many street-driven cars do fine with the factory 190°F unit.

Suspension and Handling

Coilovers and Shocks

Factory shocks on a 20+ year old Boxster are likely worn. Coilover kits from KW, Bilstein, or H&R provide adjustable ride height and damping. A quality set like KW Variant 2 or Bilstein PSS9 costs $1,500-$2,500 and dramatically improves cornering and response. For a budget option, Koni Sport shocks paired with H&R springs (drop about 1 inch) work well and cost around $800-$1,200.

Sway Bars

Thicker sway bars reduce body roll without sacrificing ride comfort. Renegade Products or Eibach offer adjustable bars for the 986. Expect to pay $300-$500 for a set (front and rear). Installation is straightforward, but you'll need an alignment afterward.

Control Arms and Bushings

Worn control arm bushings cause vague steering. Polyurethane bushings from Powerflex or Rennline tighten things up. Full control arm kits (with ball joints) from Pelican Parts or Porsche-specific suppliers cost $400-$800. For daily driving, OEM rubber bushings are quieter, but polyurethane offers longer life.

Brakes

Pads, Rotors, and Lines

For street use, high-performance brake pads like Ferodo DS2500 or Pagid RS4-2 offer improved bite and fade resistance over stock. Pair them with slotted or drilled rotors from StopTech or EBC (around $200-$400 for both axles). Stainless steel braided brake lines improve pedal feel and cost about $100-$150. Make sure to flush and bleed the system with fresh DOT 4 fluid.

Big Brake Kits

If you track the car, consider a big brake kit (BBK) from Brembo, StopTech, or AP Racing. These typically run $2,500-$5,000 for front-only setups and require 17-inch or larger wheels. For most owners, a good set of pads, rotors, and lines is sufficient.

Wheels and Tires

Lightweight Wheels

Reducing unsprung weight improves acceleration, braking, and handling. Lightweight wheels from OZ Racing, SSR, or BBS (e.g., 17x7.5 front, 18x9 rear) save 3-5 lbs per corner. Used sets are common on forums. Expect to pay $1,000-$2,500 for a good used set. Tires: Michelin Pilot Sport 4S or Continental ExtremeContact Sport are excellent performance tires. Sizes: 205/50R17 front, 255/40R17 rear (if staying 17-inch).

Interior and Maintenance

Seats and Steering Wheel

For a sportier feel, aftermarket seats like Recaro Pole Position or Cobra Misano fit the Boxster with adapter brackets (about $1,200-$2,000 per seat). A smaller diameter steering wheel from Momo or Raid costs $200-$500 but requires a hub adapter.

Common Maintenance Parts

• Water pump: Use a metal impeller pump from Porsche (Genuine) or aftermarket like Geba. Replace with thermostat and belts. ($200-$400)
• Serpentine belt and tensioner: Gates or Continental belt (~$50). Tensioner assembly from Dayco ($60-$100).
• Spark plugs and coils: NGK or Bosch plugs ($10-$20 each). Coil packs from Beru or Delphi ($50-$80 each).
• Oil separator: The 1999 Boxster is prone to failure; upgrade to air/oil separator kit from Pelican Parts ($150-$250).
• Window regulators: Common failure. Aftermarket regulators from A1 Cardone or OEM from Porsche ($100-$200 each).

Practical Recommendations

If you own a 1999 Boxster and plan to keep it for several years, prioritize reliability upgrades first: billet coolant pipes, updated water pump and thermostat, and fresh suspension bushings. For performance, start with an intake and exhaust, then consider a tune. The biggest handling improvement comes from a proper suspension setup (coilovers or shock/spring combo) and a good set of tires. When buying used aftermarket parts, inspect carefully for rust or damage, especially on suspension components. Always verify compatibility with your specific Boxster VIN (e.g., the 1999 model uses the 2.5L M96.20 engine).

For those on a budget, focus on maintenance items before power mods. A well-maintained stock Boxster is more fun than a poorly maintained modified one. Use forums like Planet-9 or Rennlist for specific part recommendations and installation tips. Remember, the 1999 Boxster is a 20+ year old car, so plan for unexpected repairs and keep a healthy emergency fund.

Finally, choose parts that match your driving style. A daily driver needs more comfort and durability, while a track car can sacrifice some ride quality for performance. Based on proven results from the Boxster community, the following parts offer excellent value: EVOMS intake, Bilstein PSS9 coilovers, Ferodo DS2500 pads, and LN Engineering coolant pipes. These upgrades will transform your 1999 Boxster into a more reliable and engaging sports car without breaking the bank.