| my personal experience is that CP is of the upper class of pistons for a few reasons. Budget wise they are not the best but quality wise they are of the best I've seen and used. They don't have a tallest top ring land and they use a standard double radial thick compression second ring which I dont like as it offers poor oil control. However the machining ques they have incorporated into their pistons is the best I've seen. Oil groove in the pin bores. Dual oiling ports. Better circlip groove for installation and retrieval. The CP piston is also one of the shortest pistons on the market. They do however weigh less than nearly all the others on the market as well. If you are going for budget I suggest the Wiseco pistons for a few reasons. Anti detonation pattern on the top ring land. The top ring land is the tallest of any aftermarket piston for our application. They use a napier second cast ring for oil control which is unsurpassed in performance. They also use a steel nitride top ring that is very robust under high boost situations. Costing a mere 550-600 you get quite a nice set of pistons and they have their own skirt coating which is nice. CP nor Ross offer this to the customer. Here are a few images of what Im referring to on the CPs and Wisecos. Both pistons I'm showing have coatings applied to the skirts that I offer for all the builds I do. I apply this coating in house. Its a dry film ceramic coating that is bonded with the skirt. These first few are of brand new CP pistons and the attributes on the pin bore.. 
These next few show the coating I apply to the skirts as well as a good view of the top ring land I was speaking about. I also coat the tops of the pistons as well with a high grade ceramic that is specifically developed for Nitrous/turbocharged applications.
Here are the images of the Wisecos with the taller top ring land and the anti detonation grooves. Notice the difference in machining as well. The CPs have a much better finish and final product as far as quality goes in comparison. 
Here are the same Wisecos I've coated for the current build I'm doing now for a customer...
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Re: Which piston is the best : Ross or CP ? - 
