The 18SS is a good truck be it your first or your 10th. Its not difficult to build and you will have the benefit of knowing exactly how it went together which will make troubleshooting later much easier. I think you'll be very happy with it.

As for the polished pipe. It does offer a decent power increase over the stock plastic but its also louder, if thats a concern.
How much are you looking to spend on a pipe?
I have a used polished pipe in excellent condition PM or email me if you are interested.