Both are cheap, but are they cheap for a reason, S1 is what I would choose, but was thinking about going to see that RS1600i myself as I have never had one

I would suggest a S2, if you ripp out interiors and dashes on either the S1 or the 16i, you will lower it's value and it's not what buying those cars are about, they are harder to come by and for the cash your paying, expect problems.

A decentish S2 can be picked up for £1500 - £2000, it's more modern, has the trim you want and parts are easier to come buy. Plus you'll have a good chance of getting a car that needs little work and can be enjoyed.

You may have found 2 bargains so by all means go and have a gander, but if you are on a budget and looking to get into a turbo for cheap £££ then head down the S2 route, I think you'll be happier.

Let us know how you get on.