which is a better cam??

My vote will be "GSC"!
You wont regret!

gsc s2 "274"

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mystotic racing have them in stock for the s2 lol. Pm him

s2 gets my vote. consider upgraded valvetrain while your at it tho

hmmm...looks like my work is done here

are the s2's really that much better then the m2's?

i cant complain about my s2's they have worked great from my stock turbo to an Fp red and now on a 6262

Btw, for the GSC S2 owners mind to share what yr cams setting spec? Exactly according to GSC spec or your own spec?

s2's all the way

they idle way better than the Cossies, they are less expensive, they make more power. All in all I am going to have to go with Yes.

any back to back test done on this?

little off topic but same question i am running a red arp studs and will upgrade springs but debating between the s2's and the fp4r's i am running gsc s1's now but going to upgrade

I have Cossies (M2's) myself. I think I probably had one of the first sets installed back in '06 on my IX RS. They have performed well for me over the years and I made good power with them. Mine also idled well and you could vaguely tell I had cams thanks to Bryan (Razorlab) who tuned me.
That said... I have seen many have good success with the S2's as well. I did upgrade my springs at install and glad I did. I personally think anytime you install cams with 11 mm of lift or higher it is a good idea. Kelfords are a good choice too. Nice to see we have so many choices now. I think just get your best deal on either of the ones mentioned and you will
be fine.