ISR Performance Turbo Kit - Mazda Miata NB 1.8 - With RS T25/28 Turbo

The ISR Performance Turbo Kit is a complete bolt-on turbocharger system for the 1.8L Mazda Miata NB (1999-2005). Built around the proven ISR RST25/28 turbocharger with a Schedule 10 tubular manifold, chassis-specific intercooler, full polished aluminum piping, and AN-fitted oil and water lines. One of the most complete affordable turbo kits available for the NB Miata platform, producing 210 RWHP at 8 PSI on a stock BP 1.8 engine.

What It Does

Turbo-swapping a Miata is a well-known path to making the chassis feel as quick as it handles, and complete kits like this one shortcut the parts-collection problem. Everything you need to bolt the turbo system to a 1.8L NB Miata is in the box: turbo, manifold, intercooler, piping, downpipe, oil and water plumbing, AFM-delete intake, and a turbo. The Schedule 10 tubular manifold resists cracking far better than cast or thin-wall tubular alternatives, which matters on a turbo Miata that'll see heat cycle abuse.

This kit is designed for use with an aftermarket ECU running on a MAP sensor (not the factory AFM/MAF), so plan for that and the supporting fueling work in your build budget.

Power Output

210 RWHP at 8 PSI of boost on a stock BP 1.8 engine. The kit is a true bolt-on, designed to deliver this output without internal engine work.

Critical Build Requirements

Aftermarket ECU required. The kit is designed for use with an aftermarket standalone or piggyback ECU running on a MAP sensor. The AFM is deleted by the included intake, so you cannot run this kit on a factory MAF-based ECU.

Hotpipe BOV flange sold separately. The included hotpipe is modular and accepts ISR, HKS, GReddy, or TiAL flanges, but the flange itself isn't in the box. Pick the flange that matches your chosen BOV.

2.5 inch hole required for intercooler piping. Routing the intercooler piping through the chassis requires drilling a 2.5 inch hole.

Fitment

• 1999-2005 Mazda Miata NB (1.8L BP engine)

What's in the Box

• 1x ISR RST25/28 turbocharger
• 1x Schedule 10 bottom-mount tubular turbo manifold
• 1x Intercooler and piping kit (polished aluminum, chassis-specific bracket)
• 1x Turbine O2 housing and downpipe
• 1x Complete oil and water turbo lines with 10AN aluminum weld bung for oil pan
• 1x AFM-delete intake with air filter

Product Details

Brand: ISR Performance

Part Number: IS-NB18TurboKit-T28

Type: Complete Bolt-On Turbo Kit (with turbo included)

Vehicle Fitment: 1999-2005 Mazda Miata NB

Engine: Mazda BP 1.8L

Turbocharger: ISR RST25/28 (included)

Manifold: Schedule 10 tubular bottom-mount

Exhaust Construction: 304 stainless steel

Intercooler: Chassis-specific with mounting bracket, polished aluminum piping

Power Output: 210 RWHP at 8 PSI on stock BP 1.8

ECU Requirement: Aftermarket ECU with MAP sensor (AFM delete)

BOV Flange: Sold separately (ISR, HKS, GReddy, or TiAL options)

Installation Note: 2.5 inch hole required for intercooler routing

Sold: Complete kit (turbo included)

Legality: Off-road and competition use only