All sounds a bit "boy racer" to me, Raj.....
Better bet, go the proper induction kit route, or shorten the pipe in the bottom of the airbox right to the edge, and fit a good proprietry filter like pipercross or K+N, don't worry about the induction roar, it will only make people think you have "wallied up" your nice car, better to keep them guessing at your cars potential then make it sound fast and dissapoint??
as for Catera rear lights, you CAN fit them, but you will have to convert the bootlid set as there are no provisions for fogs. You CAN open them up with a Dremel or similar to accept a bulb holder though..........
LED's can be fitted too, if you are proficient with a soldering iron, I have converted a few Cavalier ones to leds, it takes a fair time, but looks good. You need 5mm 1 watt leds from Maplin's, and a couple of dozen will do for Brake lights, and about 24 half-watt ones for sidelights. Don't forget to seal them in with a good silicon tube of clear after testing them.