schizo,

Meron akong OEM muffler galing Sentra GTS. Pero easily adaptable ito to any make baka gusto mo. Hindi siya kasing ingay ng sa Freemuff and mas malalim ang tunog. I just don't know kung may HP gains ka with this muffler. Php 2K only.

K&N is usually the best pero mahal. If you go with Simota, take good care of it. Never use high water or air pressure and use the proper cleaning kit at the proper intervals.

Most aftermarket intakes are CARB (California Air Resources Board?) certified, they will not affect your emissions in any significant way.

These mods are best installed in your garage by yourself. Madali lang iyan. Bonding pa kayo ng car mo.