a K&N?.....dont bother....I dynoed mine with the cheap ass Fram the K&N and without a filter.....there was less than .3 hp difference between all those. Just get the lid. Lookup Whisper Motorsports. They are in Clearwater sorta by Blue Oval Corral. You can get one direct from him for maybe 129.00. Maybe less.
As for exhaust....dont get the Borla. Too expensive for what it is. On my 98 Z28 I had a Flowmaster put in place of the stock muffler and it did a good job. That would be cheap too. Maybe $140 for muffler and install. If you want a full catback SLP make a few nice systems for cheap.