Only if your running a higher compression and big nitrous. The pair for my 598" big block were $200+, but I have 14 to 1 comp. and 300-400hp shot on the N20.
I would just like to add the problem with a MLS style gasket is there is generally no give so if you are not right on the tune and something goes wrong you normally do more damage, melt the head, pistons, damage valve train, etc... I reccomend MLS gaskets only to customers that have a good understanding with tuning, and the consequences.
The Fel-Pro MLS gasket come in a little cheaper $60/each and I find they have a little more give over the Cometic. The block and head surface have to be correct to use a MLS gasket.
I've been through 3 different head gaskets last year in a 1 month span. I tried the regular Felpro's (blew out), "stock type" Graphite Felpro's (blew out on dyno), and finally Cometic and got it to not blow out. They sealed like a mofo on my 130k mile shortblock.. whewww