BMW Catless Downpipes Guide — S55, S63, B58 & N55 Power Gains
BMW Catless Downpipes — The Complete Engine Guide
Catless downpipes are one of the highest-impact bolt-on modifications for turbocharged BMW engines. By removing the restrictive factory catalytic converters, exhaust gas exits the turbocharger housing with significantly less backpressure — meaning the turbo spools faster, exhaust gas temperatures drop, and the ECU has more headroom to add power when paired with a Stage 2 tune.
YPG Motorsport stocks catless downpipes for every major BMW performance engine — from the S55 inline-6 in the M3/M4 to the S63TU twin-turbo V8 in the M5 and M6, plus the B58 single-turbo six powering the 240i through 640i and the N55 in the original M2. This guide breaks down what to expect from each platform.
BMW S55 — M3 F80 / M4 F82 / M2 Competition
The S55 3.0L twin-turbo inline-6 is the backbone of BMW's F8x M-car lineup. With catless downpipes and a Stage 2 ECU tune, expect +30–40 HP over stock. The S55 runs two small-frame turbos with integrated wastegates, so reducing exhaust restriction has a direct effect on spool speed and mid-range torque.
The downpipes bolt on identically across F80 M3, F82 M4 coupe, and F83 M4 convertible — same exhaust routing, same hardware. Installation takes approximately 3–4 hours on a lift.
Shop: BMW M3 F80 Catless Downpipes | BMW M4 F82 Catless Downpipes
BMW S63TU — M5 F90 / F10 M5 / M6 F1x / X5M / X6M
The S63 and S63TU 4.4L twin-turbo V8 power BMW's heaviest hitters. Catless downpipes on these platforms unlock +35–50 HP with a Stage 2 tune. The F90 M5 kit includes midpipes for a complete front exhaust decat — the most comprehensive setup YPG offers for the S63TU4.
Important note: despite sharing the S63 engine family, the F85 X5M, F86 X6M, F10 M5, and F1x M6 all have chassis-specific exhaust routing. Each requires its own downpipe set — they are not interchangeable.
| Model | Engine | HP Gain (w/ Stage 2) | Price |
|---|---|---|---|
| M5 F90 + Midpipes | S63TU4 | +40–50 HP | $1,999.99 |
| F10 M5 | S63TU | +35–45 HP | $999.99 |
| M6 F12/F13/F06 | S63TU | +35–45 HP | $999.99 |
| X5M F85 | S63 | +35–45 HP | $1,500 |
| X6M F86 | S63 | +35–45 HP | $1,500 |
Shop: M5 F90 | F10 M5 | M6 F1x | X5M F85 | X6M F86
BMW B58 — 240i, 340i, 440i, 540i, 640i, X4 M40i
The B58 3.0L single-turbo inline-6 is BMW's most versatile modern engine. Catless downpipes add +25–35 HP with a Stage 2 tune across all B58-equipped models. Because the B58 uses a single, larger turbocharger, reducing exhaust restriction improves peak power and extends the power band through the upper RPM range.
The exhaust routing is shared across the F-series B58 lineup, making fitment straightforward regardless of body style. The 240i, 340i, 440i, 540i, 640i, and X4 M40i all use compatible downpipe geometry.
Shop: 240i B58 | 440i B58 | 540i B58 | 640i B58 | X4 M40i B58
BMW N55 — M2 F87
The original M2 runs the N55 3.0L single-turbo inline-6 — a proven platform that responds predictably to exhaust modifications. Catless downpipes add +20–30 HP with a Stage 2 tune. The single-turbo layout means gains are concentrated in the mid-range where the N55 already excels.
Note: the M2 N55 and M2 Competition S55 are completely different exhaust systems. Make sure you select the correct downpipe for your engine.
Shop: BMW M2 N55 Catless Downpipes
Do BMW Catless Downpipes Require a Tune?
Yes — every platform. Removing the catalytic converters without an ECU tune will trigger a persistent check engine light (CEL) from the rear O2 sensor monitoring. More importantly, without recalibrating the fueling and ignition maps, you leave power on the table. A Stage 2 tune from YPG Motorsport includes cat-delete parameters, optimized boost targets, and revised ignition timing to extract the full benefit of reduced exhaust restriction.
Installation & Shipping
All YPG Motorsport BMW downpipes are mandrel-bent stainless steel, direct bolt-on replacements with no cutting or welding required. Installation typically takes 3–4 hours on a lift. We ship worldwide via FedEx and DHL from Kuwait — GCC delivery in 2–5 business days, international in 5–10.
Questions? WhatsApp +965 9926 2020 for fitment confirmation and tune pairing recommendations.