B58 Downpipe and Parts Buying Guide - 340i, M340i, 440i, M440i, A90 Supra

The BMW B58 is the most-tuned modern BMW engine. Found in the F30 / F32 340i and 440i, the G20 / G22 M340i and M440i, the X3 and X5 40i, and the Toyota A90 Supra, the B58 takes incredibly well to bolt-on modifications. Stock 320 to 380 hp; built for over 700 hp on stock internals with the right supporting mods. KORE SPEED stocks the deepest B58 parts catalog in Canada and ships duty-free from Vancouver.

The B58 mod sequence that adds the most power per dollar

1. B58 downpipe (the must-do first mod)

Stock B58 downpipes use restrictive primary catalysts that strangle the turbo. A larger high-flow downpipe is the single biggest power gain on the B58, typically 40 to 60 whp added with a Stage 2 BM3 or MHD tune. We stock the ARM 6 inch B58 catless downpipe (largest in the market, deepest tone), the ARM 6 inch B58 catted downpipe with 200-cell high-flow cat for CEL-free operation, the MAD 5 inch B58 catted downpipe with a no-CEL guarantee, and the IRL G-series Gen 2 downpipe for the G20 / G22 platform.

2. B58 charge pipe (eliminates the boost leak)

The factory B58 charge pipe is plastic and a known failure point above 18 psi of boost. The MAD G-chassis B58 charge pipe V2 and the IRL B58 charge pipe are CNC-machined aluminum replacements that hold any boost level you throw at them.

3. B58 intake (the easy 10-15 whp gain)

For the G-chassis B58 (M340i, M440i, X3 40i, X5 40i): the MAD G-chassis intake inlet. For the F-chassis B58 (340i, 440i, M140i, M240i): the MAD B58 intake plus intake pipe kit.

4. B58 BM3 or MHD tune (unlocks everything)

The B58 has two excellent tuning platforms. Bootmod3 BM3 is the modern choice with cloud-based map editing. MHD is the long-standing community standard with the largest map library. We carry both - see our tuner comparison guide to pick the right one for your B58 chassis.

Common B58 chassis questions

What chassis is the B58 in?

F30 340i, F31 340i Touring, F32 440i, F33 440i, F36 440i Gran Coupe, F22 M240i, F23 M240i, G20 M340i, G21 M340i Touring, G22 M440i, G23 M440i, G26 M440i Gran Coupe, G42 M240i, G05 X5 40i, G06 X6 40i, G07 X7 40i, G01 X3 M40i, G02 X4 M40i, G29 Z4 M40i, A90 Toyota Supra 3.0.

How much power can a stock B58 hold?

700+ whp on stock pistons, rods, and bearings with proper supporting modifications (downpipe, charge pipe, intake, methanol or E85, BM3 or MHD tune). 500 to 550 whp is bolt-on territory on premium pump gas and a Stage 2+ tune.

Browse the full B58 catalog

Every B58 part we carry: B58 Parts collection. Common questions: FAQ page.