Why the B58 is a Tuner's Dream
BMW's B58 engine is one of the most capable platforms we work on. Found in the 340i, M240i, A90 Supra, and X3/X5 M40i, this engine responds incredibly well to simple bolt-on modifications.
Stage 1: The Basics
Start with an ECU tune (MHD Flasher) and you're looking at 380-400whp on pump gas. Add an intake for better sound and a few extra horsepower.
Stage 2: Serious Power
A catless downpipe and upgraded intercooler open up the tune significantly. Expect 420-460whp on 93 octane, and over 500whp on E30-E50 ethanol blends.
Stage 2+: Full Send
Upgraded charge pipe, methanol injection or full E85 setup, and a custom tune will push you past 500whp reliably. At this point, you may want to consider upgraded turbos for even more headroom.