Anyone know about swapping the stock supercharger pully to a lighter one to get more boost, a buddy of mine did it on his lightning and gained big time?

Well I don't know about a lighter one, but they do make a smaller one which turns the S/C faster. I think a few people have it installed on there trucks on this website but I highly doubt you are going to see gains like your friend did.

About a 20hp gain and loss of bearing life in the blower.

whats a good mod to start with... K*N filter or what... and does this smaller pulley cost much and is it really going to mess something up

You buy the pully AND the special puller to remove the old and install the new one. IMO, it's just not worth the cost, about $300-$400, and the cost of a new blower when you burn the bearings up. Maybe, and just maybe, an aftermarket K&N filter and cat-back system. I say maybe because theres no real proof they help. Just alot of seat-of-the-pants dynos.

http://www.xterraownersclub.com/ubb/ultimatebb.php?ubb=get_topic;f=70;t=000765
http://www.xterraownersclub.com/ubb/ultimatebb.php?ubb=get_topic;f=70;t=000742
http://www.xterraownersclub.com/ubb/ultimatebb.php?ubb=get_topic;f=70;t=000695
http://www.xterraownersclub.com/ubb/ultimatebb.php?ubb=get_topic;f=70;t=000610
http://www.xterraownersclub.com/ubb/ultimatebb.php?ubb=get_topic;f=70;t=000596
http://www.xterraownersclub.com/ubb/ultimatebb.php?ubb=get_topic;f=70;t=000471

etc. etc. etc...

What he said.....

I'd just go with a better intake and exhaust, I noticed gains in HP with mine and you don't have to worry about damaging the supercharger. Welcome aboard and swing by the Nexterra forum!

Your stock Supercharger is good for 7.5 lbs of boost. The smaller pulley will shorten the life of the blower big time.
I increased the boost on my Mustang from 9 to 11 and 600 bucks later, the rebuilt blower was working fine again . It is not worth the headache.

Question is how often do you floor it? I hardly ever floor mine, so spending money to add a few more top end horsepower is hardly worth it. Point being that if you don't use all the HP you have now, you don't need more. On the other hand, if you use all you got and wish for more, then that's another story.

Did you seriously just compare the X's little 3.3L to a Ford Lightning's 5.4L SC V8? Thsoe trucks are made for racing...and tell your friend he needs to monitor his A/F ratio if he doesnt want to lose his engine. The added air can cause the engine to run dangerously lean...causing detonation and consequently destroying the engine.

Yep, but most of the stock MAF sensors can compensate for the added air, especially if the engine is already S/C'ed.

Heck, half the time, the computer will overcompensate due to the fact that the air is going by faster, tricking the computer into adding even more fuel, runner her too rich!

And the fact that Nissan likes to run 'em fat anyway.

very very ture...my ol' KA24E in my hardbody shot flames galore after a portjob, and valve train was done. Ended up melting an injector. Hahaha.