I just orderd new rods and pistons. Should I upgrade valves, or can I just upgrade valve springs and retainers?

 

If you want to make big power with the new rods and pistons, you might want to upgrade the valve train, you can get 1mm larger valves, thats what i did. Then you can just get a set of good valve springs make sure you get good retainer for sure though if you do any head work! But i think the Tibby heads are pretty good, i heard of a few people taking the stock heads up to like 450hp. If you also want you can get the 1.8l cam to help reduce valve overlap which is good for boosted cars, of course you would have to have the Beta series to do this.