Sounds like you did good. Do a quick search on here for "Killer Dowel Pin or KDP". You need to get that fixed as soon as possible if it has not already been done.
As for additions, what are your plans for the truck? A set of gauges, boost and egt are always good to start off with. A good open air intake, BHAF will work just fine if you want to save some money. The exhaust which you are already doing will help also. As for the toss up between 4" or 5", it is your money but 4" is really all you need. The 5" just has a deeper sound to it.
Good luck with the truck and let us know if we can help.