It'll all depend on primary-secondary length.

There are long 4-1 and 4-1 hybrid headers that have the same torque-boosting capabilities as 4-2-1 headers... but the final decision on header type will be down to what your goals are and what space you have inside your engine bay. With the Jazz engine's exhaust manifold against the firewall, you don't have much room for long-tube headers, so you may have to settle for a shorty 4-1 or 4-2-1 design.

Speedlab carries headers for the Jazz: http://www.speedlab.com.ph/ ...prices are reasonable for a plug-and-play system, and they have dyno results to prove the effectiveness of their design.

You can also ask at http://www.hondaclub.com.ph/v4/home.php or http://www.jazzcityunited.org/ for the opinions of other members as to what's best for the Jazz.

I would also suggest locally fabricated headers, but the exhaust side of the Jazz engine is a tight place to work in, and the muffler-shops may not be willing to undertake such a project, or may take a few days to complete it.