Im going to order the 2.49 pulley but i would like to know if itabsolutely needed to change the idler pulley too to keep my stock serpentine Belt? They say it is used to remove the slack from the 2.49 swap ..if im not mistaken the 2.49 pulley only change the blower pulley and doesnt look much smaller.? * What Do you guys think

 

based on their web site, "VMP 90MM replacement idler in black" is included in their VMP 500HP package....so, I'd say yes, it's needed

 

Depends on how strong your tensioner is but I would recommend changing it to put as much pressure as possible and keep from belt slip.. 2.49 is pretty small man.

 

Alrighy thank you ill pay the xtra 70$ to get the idler. . Just making sure tho. Im stil safe with stock engine and the 2.49? Im only at 340 rwhp atm

 

That seems really, really low.... 340whp for a boosted motor? Lot of people hitting that with a head/cam package.....

 

Yeah you should be safe with a new tune and all.. You can be safe up to 500 wheel, some people go over, some stay under.. That pulley isn't going to get you anywhere near 500 so you're good..

And ehh, the M90 isn't that big and doesn't provide a whole lot of power. That's about right for a stock pullied M90.. A heads and cam can provide around 330-340 but it would be pretty extreme, the driveability won't be as great, and the band won't be as smooth.. The M90 provides a much better daily driver for a little more moeny than a head and cam package.

 

once i get the pulley, ill go to another dyno which is a dynojet not a mustang dyno and see what are my final number on a cold day, pretty sure ill be close to 400 and that should satisfy me, i just picked up the car and im really satisfied with the improvement it have, i left a nice long rubber mark while spinning whole 2nd gear until i bounce rev, damn that feel good getting it back finally.