Astra H VXR Tuning Guide
We've been tuning Astra H VXRs since we first opened our doors — it's a car we know inside out. All of our tuning packages have been developed and tested on our in-house rolling road and thoroughly validated on road and track, including the Nürburgring and our own Time Attack car.
The Z20LEH 2.0 turbo engine responds well to tuning at every stage, and there's a clear upgrade path from a simple remap right through to a fully built 300bhp+ car.
This guide walks you through each stage, what parts you need, and the power you can realistically expect.
Stock Where you're starting from
Vauxhall rated the Astra VXR at 240bhp. On our dyno, healthy standard cars typically sit right around that mark. A solid starting point for what's to come.
Stage 1 — Remap Only No hardware required
Our Stage 1 package requires no hardware upgrades at all. With careful ECU calibration we fine-tune boost, fuelling and ignition timing to produce around 255–265bhp and 280–300ft/lb — a noticeable step up in mid-range pull and throttle response.
We advise a crossover delete pipe and cone filter at this stage to get the very best from the remap, but they're not strictly essential — the remap alone delivers strong gains.
Stage 2 — Exhaust + Remap Let it breathe
At Stage 2 we need to help the car breathe more freely. The standard 2.5" exhaust system and pre-cat are the main restrictions — replacing them with a 3" exhaust system opens things up significantly.
Cobra Sport offer the full range for the Astra H VXR — from cat-back systems to full turbo-back setups in both resonated and non-resonated configurations. For Stage 2, a 3" turbo-back system gives you the best gains.
- Induction kit with crossover delete
- 3" performance exhaust system (turbo-back recommended)
- Pre-cat delete / replacement
- Custom Stage 2 remap
Stage 3 — Intercooler + Remap Reduce intake temps, unlock more boost
At Stage 3 we look to reduce intake temperatures. The standard intercooler isn't efficient enough to support higher boost levels without intake temps climbing rapidly — especially on warmer days or on track.
A larger front-mount intercooler solves this completely and allows us to safely increase boost pressure further. Airtec offer two options depending on your goals — the Stage 2 60mm core for fast road and track use, or the massive Stage 3 Gobstopper 100mm core for serious builds.
- Induction kit with crossover delete
- 3" exhaust system (from Stage 2)
- Uprated front-mount intercooler
- Custom Stage 3 remap
Stage 3+ — Inlet Manifold Maximum stock turbo power
More power can be safely added with the addition of an uprated inlet manifold. This opens up the top-end breathing and allows the engine to make the most of everything fitted so far.
At this point you're seeing 300–320bhp — the realistic limit of the standard internals on the Z20LEH.
Supporting Modifications Chassis, handling & reliability
Lowering Springs — The Eibach Sportline kit drops the car and sharpens up the handling noticeably. A great complement to any stage of tuning.
Powerflex Handling Pack — Includes front lower engine mount insert, steering rack bushes, and rear beam bushes. Tightens everything up and reduces the sloppiness that develops in the standard rubber mounts.
Oil Cooler — If you're tracking the car or running Stage 3+, an oil cooler is a sensible addition. The Airtec oil cooler kit is grill-mounted for maximum airflow and is designed to work alongside the Stage 3 Gobstopper intercooler.
Complete the Look Styling upgrades
We stock a range of styling parts for the Astra H VXR — splitters, side skirts, and more to give the car a sharper look to match the performance.
Browse all Astra H VXR Styling Parts →Quick Reference Power by stage
| Stage | Mods Required | Power | Torque |
|---|---|---|---|
| Stock | None | ~240bhp | ~236ft/lb |
| Stage 1 | Remap (+ crossover delete & filter recommended) | 255–265bhp | 280–300ft/lb |
| Stage 2 | Induction kit + 3" exhaust + pre-cat delete + remap | 270–290bhp | 300–330ft/lb |
| Stage 3 | Induction kit + intercooler + exhaust + remap | 285–305bhp | 330–350ft/lb |
| Stage 3+ | Inlet manifold + all of the above | 300–320bhp | 350+ft/lb |
All figures based on real dyno results at Wayside Performance, Coventry. Individual results may vary depending on the condition of the car, fuel quality, and ambient conditions.
Ready to Get Started?
Whether you're after a simple Stage 1 remap or planning a full Stage 3+ build, we'd love to help. All of our tuning is completely custom and carried out on our in-house rolling road in Coventry — no generic off-the-shelf maps. Every car gets a before and after dyno printout.
