Headers come with the collector size the primaries wanted, not the size your exhaust is. A reducer bolts to the collector flange and steps the diameter down cleanly, which beats a slip joint and a hose clamp and keeps the joint serviceable.

Hooker 11036HKR Header Collector Reducer Features:

• Steps a 3-1/2 in. header collector down to a 3 in. tailpipe.
• 3-bolt flange connection at the collector.
• Lets a large-collector header run into a smaller exhaust system.
• Sold as a pair.