There are multiple aftermarket company's that offer lits of great parts. It would really depend on how much you want spend on these& also brand.
For a pre tune ZZP offers the whole speed limiter removed. Thrasher, 3800 performance, w body store. I mean they all offer the same generic tune.
Headers- T.O.G. are the was to go if you want to spend the money on them. SLP is a good one also. ZZP offers a set, w body store does also.
CAM WISE, REALLY JUST HOW MODDED YOU WANA GO