Do I need to jack up my car to install this?

Yes, you'll need the vehicle lifted to access the bolts at the catalytic converter and remove the stock exhaust. A jack and jack stands or ramps are essential — don't work under a car on a bumper jack.

Does this come with new gaskets and bolts?

The assembly ships as pictured — confirm exactly what fasteners and seals are in the box before starting removal of your stock exhaust. You may need additional hardware depending on what's already at your mounting points.

Will this fit if I have an aftermarket downpipe?

This is a catback design, so it connects at the cat. If your downpipe connects to the stock catalytic converter flange, you're good. Any non-standard cat setup should be test-fitted before final assembly.