Renault exhausts are s**t, they make them out of bits of old U-boats they find floating in the channel.
Crazycup, 2.5" bore is best for the 172/182. This is the bore size of our stealth system:
http://www.k-tecracing.com/show_product.asp?id=1088
David.
^ They do, you have to be a member tho