Will this bolt straight to my factory cat, or do I need an adapter?

This system is designed as a direct catback bolt-on. Confirm the flange diameter matches your OEM catalytic converter before install — most 240SX cats are compatible, but inspect yours first to avoid ordering an adapter separately.

Do I need to weld or does it use clamps?

Stainless steel catback systems like this one typically use clamp-style connections and bolt flanges throughout — no welding needed. Hand tools and basic mechanical ability will handle the install.

Can I run this with a test pipe or do I need the cat?

This system bolts to the catalytic converter, so you'll need the cat in place for a proper seal at the mounting flange. Removing the cat requires a separate test pipe or catless downpipe — this exhaust alone won't work without it.