Insane Shafts 500HP Axles (RSX Base/EP3 Civic Si/EF K-Swap)

If you're running a K-series swap in your EF Civic or CRX, or pushing your RSX Base or EP3 Civic Si past stock power levels, your factory axles are the first thing that will let you down. Insane Shafts built the IS-015 and IS-016 specifically for this swap combination, and they're rated to handle up to 500 wheel horsepower - on the street or on track.

The difference comes down to materials and process. These axles are forged from chromoly steel and then run through a proprietary annealing and heat treatment process that most budget axle brands skip entirely. That process relieves internal stress in the metal so the shaft handles torsional load without fatiguing prematurely under repeated hard pulls. You're not just getting a stronger material - you're getting a properly engineered part.

The outer joints use 26-spline hubs, which is the correct spec for K-swapped EF chassis and for RSX Base and EP3 applications. The joints are built to OEM-style tolerances, meaning you get smooth daily-driver operation without the vibration or clunk that plagues cheaper aftermarket units. Both the inner and outer CV boots are new, sealed for long-term protection, and the kit includes new spindle nuts so you're not reusing hardware on a $500+ part.

Each kit ships as a complete left and right pair - IS-015 (driver) and IS-016 (passenger). You get both axles, new spindle nuts, and removable ABS rings where applicable. No core charge, no partial kits.

Insane Shafts backs every axle with an 18-month limited warranty. These are built to be a long-term solution for your K-swap build, not a placeholder until you find something better.

Fits: 2002-2006 Acura RSX Base, 2002-2005 Honda Civic Si (EP3), 1988-1991 Honda Civic / CR-X with K-series swap. Requires K20 RSX/EP3 half-shaft. Does NOT fit RSX Type-S or Type-R.