loosing boost

[slifko52]

I have changed out my stock pulley and put a 2.8 on it with an undersized belt from napa worked fine till now but i believe i have belt slip, but my scaner is telling me rail pressure sen. is having a fault reading and the other code is over boosting, do you suggest to get an idler pulley for the belt

 

[Bdubbs]

It's always recommended having a aux idler pulley on. You may have to change belts again when adding a aux pulley. Whats the part # for your current belt? So is your check engine light on, throwing codes?

Check link below for belt sizing.
http://www.stangshiftergaskets.com/belt_selection_guide.htm

 

[MoKo_03SVT]

if you think the belt is where your problem is, then why buy an idler? get a new belt, that is the right size!

i ran a 2.8 upper, with stock idlers and ZERO belt slip/loss of boost.

i found the correct size of belt that i would need on cobra bobs website. the brand i went with was/is gates. i picked it up at the o'reillys by my house for like $30-35

here is the link..

Stang Shifter Gaskets

edit: not saying an idler wouldnt help. just saying if the problem = the belt...then fix the belt/problem