for performance the simplest mod is an exhaust. if you go for an injen or other brand exhaust... your pretty much paying for the polished stainless look. if you can get past the polished look a good exhaust shop can make you a cat back. older elements formula was 2 1/4-2 1/2 inch pipe with a resonator and 21 inch long muffler. the brand of muffler should effect sound level but if you stick to the muffler length it shouldnt get a cruise drone.
im currently looking into a full length header install on mine when I make progress il post results.
you can get an injen cold air intake 07+ should fit ours. (make sure you order one that has bracket for maf, rest of pipe is the same for 2003-2010)
or just get a k&n factory filter. K&N AIR FILTER 33-2343, 2006-09 HONDA CIVIC SI, ELEMENT 2007-2010
grill replacement. unfortinatly we have to mod our grill ourselves. removing the H can either be simple or lots of work. and price can range.
im going for a factory look so my mod is the most costly and time consuming. im taking 2 grills and making 1 (cutting out emblem section and replacing with a side section same with factory mesh)
but you can mod your grill in many ways also remove the chrome H and install mesh to the front of grill for a flush look like this (you would need to bend the edge of mesh flat on the back. and bend back out. so it stays 1 piece and has an L shaped mounting flange on back.
you can cut the H out of the grill,cut the mesh out and patch grill and install mesh from rear for the recessed look
it all depends how much work you want to put in and money. as you can see in the last one. the section you repair in the grill can be taped off and sprayed black if you cant spray yourself or dont want to have your whole grill repainted.
if you want to get it then by all means do it. ive heard chipmagic is pretty good but it should be installed by a pro to look decent. now this is just personal opinion but there is no helping an element from front end damage. on my SC if i used the clear bra protector stuff. ide have to cover my mirrors,windshield trim,front edge of hood,grill,and whole front bumper. The cost varies. A typical shop gets anywhere from $175.00 - $250.00 for just the hood and the front corners of the fenders. The bumper is the most complex and can cost $200.00 - $300.00 more. Then you have the mirrors and headlights to consider. The total costs can add up to over $750.00 for a "full front-end wrap."
The less expensive brands of plastic clear bra may yellow with age and can sometimes peel up. The plastic leaves a distinct line that can trap dirt and wax. If you have existing chips, the plastic clear bra forms bubbles over the chips and the damage is even more visible.
that would be costly and while it protects like its supposed to it isnt as shiny as the paint. for the cost of the install ide rather pickup a cheap airbrush kit and a bottle of touchup paint. just inspect it often