Restore dependable spark isolation and secure coil-to-plug contact with the ThunderCore PRO Coil Boot Kit 900-P2101-4. This OE-replacement kit is a direct-fit for the 2004-2006 Subaru Baja, 2004-2010 Subaru Forester, 2005-2009 Subaru Legacy, 2005-2009 Subaru Outback, 2006 Saab 9-2X, and 2006-2014 Subaru Impreza — see the "Vehicles it fits" section for engine specifics.
In coil-on-plug (COP) and coil-near-plug (CNP) systems, the boot forms the insulative path between the ignition coil and the spark plug. Heat, vibration, and chemical exposure can degrade boots over time, leading to arc-through, misfires, or hard starting. If worn or cracked boots are the cause, this kit replaces them to help restore proper high-voltage insulation.
- Heat & chemical resistant: built from high-temp silicone and reinforced materials to resist oil, fuel, and under-hood heat.
- OE-replacement quality: engineered to match OE dielectric strength, boot length, and connector geometry.
- Restores insulation: replaces degraded boots to support proper spark isolation and limit voltage loss.
- Complete kit coverage: includes the boots, springs, and insulators needed for full-cylinder service — ideal for ignition tune-ups or preventative maintenance.
Interchange: 184082 · 9007S
Frequently Asked Questions
What is the ThunderCore PRO 900-P2101-4?
It's an OE-replacement Coil Boot Kit that supplies the boots, springs, and insulators needed to restore spark insulation between the ignition coils and spark plugs for full-cylinder service.
Which vehicles does this kit fit?
It fits the 2004-2006 Subaru Baja, 2004-2010 Subaru Forester, 2005-2009 Subaru Legacy and Outback, 2006 Saab 9-2X, and 2006-2014 Subaru Impreza. Check the "Vehicles it fits" section for engine details.
What does a coil boot do?
In coil-on-plug and coil-near-plug systems, the boot forms the insulative path between the ignition coil and the spark plug, providing high-voltage insulation and secure coil-to-plug contact.
What are the signs the boots may need replacing?
Cracked or degraded boots, arc-through, misfires, or hard starting can be signs. Diagnose the cause first, since these symptoms can have other sources.
What's included in the kit?
The kit includes the boots, springs, and insulators for full-cylinder service, making it suited to ignition tune-ups or preventative maintenance.
