It will work, you just need the right fittings since the 03 cobra hoses are a little bit bigger. I have the gords ford 03 cobra HE on my Saleen S2 blower now. Here's a pic of my S2 HE vs the Gords.
LFP will work. It just needs to have some brackets welded on so that the stock saleen fans have something to mount to. No big deal my Neighbor is doing it for free. I dont have it on yet, but its bigger than te Saleen HE so it should help keeps things cool.
I don't have a before / after dyno so I can't say. I don't think it help mine out that much, the intercooler would have probably been better to do since I have the series 2. That is quite a bit more work though. If it keeps things running safer then it's more than worth it to me.
I ordered the additional brackets from Gord, but we were able to use the Saleen bracket on it.