If you're looking for a good chin spolier I can recomend the Blitz version. It's slightly deeper than the original and protrudes further. Also it's quite flexible (I've only managed to break one so far).
I've just noticed a chunk out of my lower spoiler. I must have done it over the weekend but I can't for the life of me remember when. Anyway, I've had a quick look around the net to see if I can find a replacement:
Unless I'm going completely blind then I can't find anything on this site for a lower spoiler - please let me know if I'm wrong
They have a NISMO Lower Front Spoiler - I'll ring tomorrow to find out how much and how long to import
I'll keep looking to see what I can find. Please let me know if anyone finds anything more.