I am have my engine rebuild and want to do some upgrades to it after the motor is done.... Would a k and n cold air intake and straight pipe after the cat be good... And would it sound good

 

K&N cold air intakes won't work.

 

Do a cowl intake! Much better and also very functional keeping water out instead of havin a gaudy silly lookin snorkel. There are alot of DIY posts about cowl intake as well. Bonus it gives you more room to add an extra battery perhaps?

 

Get a bigger cam a header and a cat back exhaust kit.