Great question and you can do a serious search on this too. Anyway- plan to spend ~$1000 for the whole Neuspeed spring/Koni shock setup and a Neuspeed front upper tower bar. If you have a 5th gen the rear upper bar is harder to find as Neuspeed does not make one. I have a Spoon and know that there are several others out there for 5th gen's. Yes the bars do help stiffen the chassis. Personally, I would not considewr the DC Sports bars as they flex.

Depending on how much you lower the car, you may need Camber kits to correct the alignment. The rule of thumb is that for each 1" of drop the Camber will go negative by 0.84 degrees from wherever you started. You MUST have a 4-wheel alignment after the car is lowered to determine the setting and to reset the Toe-in. ANY work done on the suspension and this is something that you should do. Hope this helps get you started.