Installing a set of Borla GT-R downpipes is one of the most effective bolt-on upgrades you can perform on a Nissan GT-R. By reducing the backpressure created by the restrictive factory downpipes, you unlock significant horsepower gains, quicker turbo spool, and a more aggressive exhaust note. However, achieving a perfect fit and extracting the best sound requires attention to detail, proper tools, and a systematic approach. This guide covers everything from selecting the right hardware to troubleshooting common installation pitfalls, so you can complete the job with confidence and enjoy your GT-R at its full potential.

Tools and Materials you will need

Before you begin, gather all the tools and supplies. Many GT-R owners find that having the correct socket sizes and quality fasteners makes the difference between a two-hour job and a day-long headache.

  • Socket set with extensions: 10mm, 12mm, 14mm, and 17mm sockets (deep and shallow). A 3/8” drive ratchet works well for most bolts, but a 1/2” breaker bar will help with stubborn nuts.
  • Torque wrench: Critical for tightening bolts to the manufacturer’s specifications without overtorquing and warping flanges.
  • O2 sensor socket (22mm offset) – the factory oxygen sensors are notoriously tight.
  • Penetrating oil (e.g., PB Blaster or Liquid Wrench) – soak all bolts the night before to ease removal of rusted fasteners.
  • Jack and jack stands – the GT-R’s ground clearance is low; you need at least 18 inches of lift to work comfortably.
  • Safety glasses and mechanic’s gloves – falling debris and sharp heat shields are a real hazard.
  • New gaskets (turbo outlet and mid-pipe side) – Borla supplies gaskets, but having a spare set of OEM or high-quality aftermarket gaskets is recommended.
  • Anti-seize compound – essential for preventing thread galling on stainless steel bolts.
  • Heat shield removal tools – usually a 10mm nut driver or small socket.

If your car has high mileage, consider replacing the turbo-to-downpipe studs and nuts with new fasteners. Borla downpipes are made from 304 stainless steel and use a 3-bolt flange; having fresh hardware ensures a leak-free seal.

Preparation and safety

Park the GT-R on a level concrete surface and allow the exhaust system to cool completely – even a warm catalytic converter can cause burns. Engage the parking brake and place wheel chocks behind the rear tires. Disconnect the negative battery terminal to avoid accidentally shorting any circuits while working near the oxygen sensor wiring.

Raise the vehicle using a jack at the reinforced jack points. Secure it on four heavy-duty jack stands placed under the frame rails. Never rely on the jack alone. If you have a QuickJack or lift, even better. Once the car is safely raised, double-check stability before sliding underneath.

Removing the stock downpipes

The factory GT-R downpipes are located directly below the turbos, connecting the turbo outlet to the mid-pipe. Access is tight, especially on the passenger side where the air conditioning lines run nearby. Follow these steps carefully to avoid damaging sensors or exhaust components.

Step 1: Remove heat shields

Use a 10mm socket to remove the bolts securing the heat shields over the downpipes. There are usually three shields: one above each downpipe and one covering the mid-pipe connection. Keep the hardware organized – you will reinstall it later.

Step 2: Disconnect the oxygen sensors

The GT-R has two O2 sensors on the downpipes – one front (pre-turbo) and one rear (post-turbo). Use an O2 sensor socket to unscrew them from the bung. Disconnect the electrical connectors behind the engine bay fuse box (driver side) and along the frame rail (passenger side). Use penetrating oil if the sensors are seized. Carefully thread them out; they are easily stripped.

Step 3: Remove the mid-pipe connection

Loosen the two 14mm bolts connecting the downpipe to the mid-pipe. The factory uses a spring-loaded flange; you may need to compress the springs with a pry bar to relieve tension. Careful not to drop the springs and washers.

Step 4: Unbolt the downpipes from the turbos

Using a 14mm socket and extension, reach the four bolts on each side connecting the downpipe to the turbo exhaust housing. These bolts are often very tight – use a breaker bar and penetrating oil. Work back and forth to avoid snapping the studs. If you break a stud, you will need to extract it, which adds significant time. Patience is key.

Step 5: Remove the downpipes

Once all bolts are removed, wiggle the downpipe free. The rear-diff side is the easiest; the front side may require slight rotation to clear the frame. Check the factory gaskets – they are usually crush-style and should be replaced. Clean the turbo outlet flanges with a wire brush until all old gasket material is removed.

Installing the Borla GT-R downpipes

Borla downpipes are designed as a direct-fit upgrade, but proper technique ensures they seal perfectly and deliver the sound you expect.

Prepare the flanges

Apply a thin layer of anti-seize compound to the threads of all bolts. Inspect the supplied gaskets – Borla includes high-quality multi-layer steel gaskets. Fit the gasket onto the turbo outlet studs first, making sure it sits flush. Use a small dab of grease to hold the gasket in place if needed.

Mount the downpipes

Place the Borla downpipe over the turbo studs, aligning the flange. Install the four nuts hand-tight. Then connect the downpipe to the mid-pipe flange using the supplied bolts and new gaskets. Do not fully tighten any fastener yet – leave everything loose to allow for adjustment and to reduce binding.

Once both ends are loosely fitted, go back and torque the turbo flange nuts in a crisscross pattern to 35 ft-lb (follow Borla’s instructions; typical range is 30-40 ft-lb). Then torque the mid-pipe connection bolts to 40 ft-lb. Reinstall the oxygen sensors, threading them by hand first to avoid cross-threading, then tighten to 30 ft-lb (never use anti-seize on oxygen sensor threads unless specifically recommended).

Reinstall heat shields

Refit all heat shields using the original hardware. Ensure no wiring or hoses are pinched between the shield and the downpipe. For a cleaner look, many owners opt to leave the lower heat shields off – but this increases cabin heat and may risk melting nearby components. Replacement is recommended.

Final steps and initial startup

Reconnect the battery. Start the engine and let it idle for a minute. Listen for exhaust leaks – a ticking sound often indicates a flange leak. Inspect all joints with a flashlight. If you have a smoke machine or a soapy-water spray bottle, check the mid-pipe connections. Rev the engine gently to 3000 rpm to pressurize the system. If you detect a leak, tighten the affected bolts slightly (about 5 ft-lb increments) until the leak stops. Do not overtighten to avoid cracking the Borla flanges.

After confirming no leaks, lower the vehicle to the ground and tighten the lug nuts to 105 ft-lb. Take the car for a short test drive, monitoring for any check engine light (CEL) related to the O2 sensors. Because downpipes eliminate the secondary catalytic converters, you may trigger a P0420 or P0430 code – a common issue resolved through ECU tuning (see tuning section below).

Tuning considerations for Borla downpipes

Installing any downpipe that removes or alters the catalytic converters requires engine management recalibration. The GT-R’s ECU uses wideband oxygen sensors and adjusts fuel trims based on exhaust readings. Without a tune, the car will likely run rich, trigger a CEL, and may enter limp mode. Even if you use spacers to trick the rear O2 sensors, the factory mapping is not optimized for the increased flow. A proper Ecutek or Cobb Accessport tune from a reputable Nissan specialist will unlock the full horsepower gains (typically 30-50 whp with a tune) and eliminate the CEL.

Many tuners suggest logging fuel trims immediately after installation. Borla downpipes, combined with a cat-back exhaust and cold air intakes, can yield over 600 whp on pump gas with a conservative tune. For more information, consult resources like Borla’s official product page for application-specific dyno charts, or visit a dedicated Nissan GT-R forum like GT-R Life for owner experience threads.

Tips for achieving the perfect sound

Borla downpipes are known for their deep, aggressive tone without excessive drone. However, sound is subjective and depends on the rest of your exhaust system. Here are practical tips to fine-tune your GT-R’s voice:

  • Match the mid-pipe and mufflers: If you run a fully cat-back exhaust with resonators and a rear section, the downpipes will add volume but not obnoxious rasp. A stock mid-pipe combined with Borla downpipes may still sound civilized.
  • Check for exhaust hanger wear: Old rubber hangers allow the exhaust to vibrate and cause drone. Replace them with polyurethane units for better isolation.
  • Use new gaskets at every connection: A minor leak at the turbo outlet creates a high-pitched whistle that many mistake for a turbo surge. Ensure a complete seal.
  • Consider heat wrapping: Wrapping the downpipes with DEI titanium wrap reduces under-hood temperatures and can slightly alter the exhaust note by keeping gases denser until they exit.
  • Break-in period: Stainless steel exhaust components take about 200 miles to “season.” The sound may become deeper and quieter as carbon builds up on the inner walls.

If you want to compare sound clips, Borla’s product page often includes audio and video samples from real customer installations. Use these as a benchmark.

Common installation pitfalls and how to avoid them

Even with a direct-fit product, the 120-degree temperature cycles and tight packaging on a GT-R can cause frustration. Below are the most frequent issues and their solutions:

Broken exhaust studs

The four studs at each turbo outlet are exposed to extreme heat. Over years of expansion and contraction, they become brittle. If a stud snaps, use a stud extractor or weld a nut onto the remaining stub. To prevent this, soak the studs with penetrating oil and heat them with a propane torch before removal. Always use new OEM studs and nuts during reassembly.

Misalignment with the mid-pipe

Occasionally, aftermarket downpipes shift the mid-pipe downward, causing the muffler tips to hit the rear valance. Loosen all connections, then tighten in sequence: turbo flange first, then mid-pipe, then hangers. This way the system self-aligns.

O2 sensor wiring short

If you route the O2 sensor wires too close to the downpipe, the heat shield will melt the insulation. Secure the wiring with zip ties to the factory loom, keeping at least 1 inch of clearance.

Check engine light without a tune

As mentioned, you can install O2 sensor spacers (angled adapters) to move the sensor out of the exhaust stream, but this only delays the CEL. A proper tune is the only permanent solution. Cobb Tuning offers off-the-shelf maps for the GT-R that work with most downpipes, though a custom dyno tune is preferred.

Maintenance and long-term care

Borla downpipes are constructed from T-304 stainless steel, which resists corrosion but may develop a golden or blue discoloration over time due to heat. This is cosmetic and does not affect performance. To keep them looking good, wipe down the visible surfaces with a metal polish during oil changes. More importantly, annually inspect the flange bolts for looseness. The extreme thermal cycling can cause fasteners to back off slightly; re-torquing them to spec once a year ensures a leak-free seal. If you live in a region that uses road salt, consider applying a ceramic coating to the downpipes before installation to prevent surface rust on the welds.

When to call a professional

While a DIY enthusiast with a decent tool set can install Borla downpipes in a weekend, certain factors may warrant professional help: a heavily rusted underbody, lack of access to a lift, or a previous repair that used thread locker on the turbo bolts. Hourly rates at a specialty Nissan shop run $100–150, and a typical install takes 3–5 hours. Considering the cost of a tow if you snap a stud, many owners choose to have the work done by a certified technician. However, with preparation and patience, the satisfaction of doing it yourself is unmatched.

Upgrading to Borla GT-R downpipes transforms the driving experience. The quicker boost response and deeper exhaust note make every trip behind the wheel feel like a track session. Follow the steps outlined here, invest in quality tools and gaskets, and do not skip the tune. Your GT-R will reward you with consistent performance and a sound that commands respect.