Installing a JDM cat-back exhaust is a weekend project that delivers immediate results: more power, less weight, and the signature JDM exhaust note. This guide covers installing HKS Hi-Power, Fujitsubo Authorize S/Legalis R, and Tomei Expreme Ti cat-back exhaust systems on JDM cars including Nissan Silvia S14/S15, Honda Civic EK/DC5, Toyota Supra JZA80, Subaru WRX STI, and Mitsubishi Evo.

Tools Required

• Vehicle ramps or axle stands (minimum 4 stands recommended)
• Socket set: 10mm, 12mm, 14mm, 17mm
• Exhaust socket set (with rubber insert to protect O2 sensor)
• Penetrating oil (apply to all exhaust bolts 30+ minutes before starting)
• Wire brush (clean flange surfaces)
• Copper anti-seize compound
• New exhaust gaskets (always replace — never reuse old gaskets)
• Safety glasses and heat-resistant gloves

Step 1: Safety and Preparation

Always work on a cold exhaust. Exhaust components retain heat for hours after driving — burns from exhaust pipes are serious. Apply penetrating oil (WD-40 Specialist or PB Blaster) to all exhaust flange bolts and clamps at least 30 minutes before starting. For heavily rusted exhausts, apply penetrating oil and leave overnight for best results.

Step 2: Raise and Support the Vehicle

Raise the vehicle high enough to comfortably access the full underside. Use four axle stands positioned at the manufacturer's designated jacking points. Never work under a vehicle supported only by a floor jack or ramps without stands. Confirm the vehicle is stable before crawling underneath.

Step 3: Remove the Stock Exhaust System

Working from back to front: remove the rear muffler/tailpipe section first. Most cat-back systems connect to the catalytic converter with a gasket and two bolts (flange connection) or a sleeve clamp. Identify where the cat-back begins — typically directly after the catalytic converter.

Remove the rear section: unbolt the flange connection or loosen the sleeve clamp at the front of the cat-back. The exhaust will hang from rubber hangers — use a flat pry bar or exhaust hanger removal tool to pull each hanger off its post. Work from rear to front, removing each rubber hanger as you slide the exhaust rearward. Have an assistant support the system as it comes free — cat-back systems on JDM sports cars typically weigh 8–15 kg.

Step 4: Install HKS Hi-Power Cat-Back

The HKS Hi-Power is a bolt-on replacement designed to match OEM flange positions exactly:

1. Clean the catalytic converter flange face with a wire brush. Install a new gasket — never reuse the old one
2. Offer up the HKS front pipe section and start the flange bolts by hand to confirm alignment
3. Thread the HKS rubber hangers onto the factory hanger posts — apply silicone spray to help hangers slide on
4. Once all hangers are on and the front flange is aligned, tighten the flange bolts evenly in a cross pattern to 45–50 Nm
5. Apply copper anti-seize to all bolt threads before tightening — this makes future removal much easier
6. The HKS oval muffler tip should exit centrally in the rear bumper cutout. If it doesn't, adjust hanger tension before final tightening

Step 5: Install Fujitsubo Authorize S or Legalis R

Fujitsubo exhausts are known for precision engineering and exact OEM fitment. The installation is identical to HKS, but Fujitsubo systems often include adjustable hangers:

1. After connecting the front flange and threading all hangers, adjust the Fujitsubo adjustable hangers so the exhaust hangs level
2. The Legalis R has a larger diameter mid-pipe than the Authorize S — ensure it doesn't contact the underfloor or heat shields
3. Torque the flange bolts to 45–50 Nm and the Fujitsubo hanger bolts to 25 Nm

Step 6: Install Tomei Expreme Ti (Titanium)

The Tomei Expreme Ti is a titanium system and requires slightly different handling:

1. Titanium is softer than stainless — do NOT use an impact wrench on titanium bolts. Hand torque only
2. Use titanium-specific anti-seize compound (copper anti-seize can react with titanium at high temperatures)
3. Torque titanium flange bolts to 35–40 Nm only — over-tightening titanium bolts causes thread damage
4. The Tomei Ti system will discolour (blue/gold haze) after first use — this is normal and is called heat patina. It's considered desirable by JDM enthusiasts

Step 7: Start the Engine and Check for Leaks

Start the engine and listen for exhaust leaks — a ticking sound at the flange indicates a leak. With the engine running, carefully check the flange connection (do NOT touch hot components). An exhaust leak sounds like a rhythmic tick that increases with RPM. If present, re-torque the flange bolts evenly. All leaks must be eliminated before driving.

Buy Genuine JDM Exhausts — Worldwide Shipping

At Grovexo JDM, we stock authentic HKS Hi-Power, Fujitsubo, Tomei Expreme Ti, and Trust/GReddy cat-back systems with worldwide shipping. Search keywords: how to install cat back exhaust, JDM exhaust installation guide, HKS exhaust install, Fujitsubo exhaust fitting, Tomei Expreme Ti installation, cat back exhaust how to fit, JDM exhaust replacement guide, how to change exhaust system JDM.