I replaced it because it was making noise. I didn't notice any gains . Heres a quick reference on taking it apart - http://www.rollingperformance.com/snoutrebuild.htm
Theres another tutorial , but I couldn't find it, its from a cardomain page .
Basically, this is what I did -
1. disconnect the battery (8mm socket)
2. Take both belts off (just off the alternator & supercharger pulleys). You'll need a 15mm socket , #T50 star socket & 1/2" drive rachet(its easier to use the 1/2" rachet for the tensioners)
3. Take the altenator off. There are 3 bolts on the front (13mm, short & deep well sockets), one is underneath the altenator pulley(it looks like a bracket, but is part of the altenator.
There is a small bolt & nut on the back of the altenator. There is also a plug which needs to be unplugged.
4. Time to drain the */C oil out. Since the person I was working with already had done these numerous times, he had his own tool made up to drain the oil. It was a turkey baster with a long rubber hose attached at the end of it. It took about 3-4 times with the turkey baster to get all the oil out, and be prepared for the stench (puke smell) . I can't remember what size the bolt was for the drain plug,but I used a small allen wrench to get it out.
5. Once drained, you need to take the 10 bolts out that hold the snout on. They are all 10mm . You will need short & deep well 10mm sockets, as well as various extensions (small to large) & a swivel socket. The only PITA is getting the bolt out underneath the snout.
6. Once all the bolts are out, lightly tap on the snout to get it off. Tap in various spots with a rubber mallet. Put a rag or paper towls underneath the snout to catch any excess oil that may be left. When using the mallet, you will notice that it looks like there is a spacer between the snout & supercharger , you don't want that middle section coming out with the snout.
7. With the snout off, just pull the old coupler off . Put a little oil on the insides of all the holes in the new coupler and press it flush against where it mounts on the inside of the snout. I used brake cleaner to clean the inside & outside of the snout. Clean any of the old gasket off.
8. Put a small bead of black RTV gasket sealant around where the gasket was on the snout. Line up the snout with the */C and put it on, while using your hand on the */C pulley to line up the coupler with the pins on the rotor(on the */C) . Put a couple of the bolts back in (I used 2 of the lower ones on the side & a couple of the top ones) and slowly tighten them up so theres no gap inbetween the snout & */C . Once there wasn't any gap, I put all the other bolts back in and tightened them with a torque wrench .
9. With the snout back on & up to spec, put the altenator back on.
10. Put the belts back on & connect the battery. Use the turkey baster again and add the new oil . Put the plug back on and start the car to see if theres any leaks.