Did you end up buying the exhaust off ebay?
You dont need a bypass valve, unless you drive though every single puddle you see and rev the engine.
Cheapest is make yourself a homedepot intake and get a good filter. The filter might make it cost more than the ebay ones but it will be a lot better.
Write up for NT homedepot intake:
http://www.2gnt.com/nuke/modules.php...ticle&artid=80