ISR Performance 3" Turbine Outlet O2 Housing - Nissan SR20DET S13/S14

The ISR Performance 3-inch Turbine Outlet O2 Housing is a high-flow replacement for the restrictive factory O2 housing on Nissan SR20DET turbos. Stepping up to a 3-inch outlet reduces post-turbine backpressure, helps the turbo spool more efficiently, and opens up the rest of the exhaust system for real flow gains. Double-welded inside and out with a brushed finish.

What It Does

The factory O2 housing on the SR20DET is a known restriction point that bottlenecks even mild bolt-on builds. This ISR housing replaces it with a 3-inch outlet, which is the right size for a built SR running an upgraded turbo, larger downpipe, and 3-inch exhaust. Less backpressure on the turbine wheel means quicker spool and more usable power throughout the RPM range.

Fitment

• Nissan SR20DET (S13 Redtop, S14 Notchtop, S14 Blacktop, S15)
• Any SR20DET swap into S13 or S14 240SX
• Compatible with the factory 3-bolt turbine outlet flange

Important clearance note: The 3-inch outlet diameter is larger than stock and may require minor clearance work or modification near the bell housing, transmission tunnel, or downpipe flange depending on your specific chassis and transmission combination. Always test-fit before final installation.

Installation Notes

Reuses the existing stock turbine housing studs and nuts. No additional hardware needed on the turbo side.

What's in the Box

• 1x ISR Performance 3-inch turbine outlet O2 housing
• 3x Studs (M10 x 1.5, 1-3/4 inch length)
• 1x 5-bolt gasket
• 1x 3-bolt gasket

Product Details

Brand: ISR Performance

Part Number: IS-O2-SR3IN-w/adpt

Type: Turbine Outlet / O2 Housing

Engine Fitment: Nissan SR20DET (all variants)

Outlet Diameter: 3-inch

Turbo Side Flange: Factory 3-bolt SR20DET

Stud Thread Pitch: M10 x 1.5

Stud Length: 1-3/4 inch

Construction: Double-welded inside and out

Finish: Brushed

Clearance: May require minor modification for bell housing or downpipe clearance

Hardware: 3x studs and gaskets included; reuses factory turbine housing nuts

Sold: Individually

Legality: Off-road and competition use only