5502428: These are a very good fast road cam which will work with the standard ecu. We would recommend the ecu is mapped once the cams are fitted and gains of 10-12bhp can usually be seen once the ecu is mapped. The idle speed is also very smooth with these cams. Will work with the standard hydraulic followers and valve springs.
5502421: These are the next step up from the 428 cams and they will work with the standard ecu with specialist mapping. Power gains are slightly higher at 12-15bhp and the idle speed will not be quite as smooth as that on the standard or 428 cams. Will work with the standard hydraulic followers and valve springs.
5502420: This is the Renault Sport Group N profile and they are machined to the maximum limits allowed. Will work with the standard hydraulic followers and valve springs.
5502422: These cams will require an aftermarket ecu solution as the standard ecu will not be able to run them. Will work with standard hydraulic followers but uprated valve springs required.
5502423: These are the cams we have used to great effect in the race engine we have built for a customer's rally car, more details of which you can see here:
http://www.k-tecracing.com/news.asp?b=true&nav=3 they will work with the standard hydraulic followers but will require uprated valve springs.
5502551, 5502552, 5502553: High performance cams aimed at race engines. Ideally need solid lifters and uprated valve springs.
@the courtesy of K Tec Racing!