BMW Turbo Downpipe Gasket 4.5" - B58 - 18328612538

OE replacement turbo-to-downpipe exhaust gasket (4.5") for all BMW B58 turbocharged engines and the Toyota GR Supra. Direct replacement for BMW OE part #18328612538. This crush-style gasket seals the turbocharger exhaust outlet connection, preventing leaks and maintaining exhaust efficiency. Single-use - replace whenever the exhaust connection is separated during service.

Gaskets Required Per Vehicle

All vehicles listed below use a single-turbocharger B58 engine and require 1 gasket per vehicle. Sold individually - order 1 gasket per turbo outlet.

Specifications

Vehicle Fitment

What's Included

• 1x Turbo-to-downpipe gasket (4.5", OE #18328612538)

One gasket per vehicle - all listed engines are single-turbocharger.

Why Replace This Gasket?

This is a single-use crush seal and should not be reused. The gasket deforms on initial installation to create the seal - once compressed, it cannot create the same airtight bond a second time.

Reinstalling an old gasket can cause:

• Exhaust leaks at the turbo-to-downpipe connection
• Reduced engine efficiency and turbo response
• Unwanted exhaust noise, ticking, or hissing
• Check engine lights from O2 sensor readings

Always replace with a new gasket during exhaust, downpipe, or turbo service.

Need a Different Size?

OneFastShop offers turbo-to-downpipe gaskets for other BMW turbocharged engines:

• 3.5" Gasket (OE #18307553601) - for N54, S55, S58, N63, S63, S68, N74 engines (M3, M4, M5, M8, X5M, X6M, 750i, etc.)
• 4" Gasket (OE #18307581970) - for N20, N26, N55, B46, B48 engines (228i, 230i, 320i, 328i, 330i, 428i, 430i, 528i, 530i, M2 F87, X1, X3, MINI Cooper, etc.)

Match the gasket size to your engine before ordering.

Shipping

• In-stock orders placed before 3 PM EST ship the same day — everything else ships within 24 hours.
• Standard, expedited, and overnight options at checkout.
• Oversized items ship by freight and take longer.
• Backordered items ship as soon as stock lands — contact us for lead times.
• International orders: prices do not include VAT, duties, or import fees. Your country charges these at import and they are the buyer’s responsibility.

Returns

• 30-day returns on new, uninstalled items in original packaging with all hardware.
• Standard returns: 8% restocking fee, buyer pays return shipping. Both waived if the item is defective or we made the error.
• Installed or used parts can’t be returned — confirm fitment before you install.
• Special orders and custom items are final sale.
• Email us for return authorization before shipping anything back.

Full details: Shipping Policy · Refund Policy