Posi Port install - have questions

[Excessv]

Ok I have almost everything to do this install. I do however have a couple questions.
Here are the pulleys I have :
* 2.93 Steeda Upper (came on car)- Steeda Interchangable Blower Pulley System for 2003-2004 Cobra Mustang 555-3332 555-3333 555-3334
OR
* 2.73 that came on the Posi Ported Eaton

* Steeda Blower Belt Tensioner (came on car)- Steeda Blower Belt Tensioner for 2003-2004 Ford Cobra Mustang 555-3340

*3.5 Metco Alt Pulley - Metco 03-04 Cobra Alternator Pulley 6lb Lower Pulley (3.50) [MAP3500] : Lethal Performance, Performance parts for Ford Mustangs

Question is what other idler pulleys will maximize my setup? 90mm or 100
Should I just get a Metco kit - Metco Motorsports 4-Piece Idler Kit w/Single Ball Bearing Idlers [MCR-4PIECES] : Lethal Performance, Performance parts for Ford Mustangs or can I just add the 3 other pullies that I need.
Any help would be great!

Forgot to mention I have a 4lb lower & a 2lb ring...... DUH.....

 

[cobracide]

Hold on there bud.. why the alt pulley? Are you secretly getting a lower? No alt pulley needed with an upper. With a Posi ported, yeah a 2.76 upper will run good. More conservative people choose the 2.9x but that one is good. Just a bit more heat so watch your temps regardless.

However, having said that, I underspin my alt with a 3.5" (for a 6#) lower instead of the 3.2" that keeps the alt near stock speed with a 2-4#.

Nice choice on the idlers but if you have the cash, go double bearing. Get the four piece, you want the snub idler and that's it!

 

[timspony]

^^^^ That would be correct!!! ... Go with a 2.76" upper!

 

[Excessv]

Hold on there bud.. why the alt pulley? Are you secretly getting a lower? No alt pulley needed with an upper. With a Posi ported, yeah a 2.76 upper will run good. More conservative people choose the 2.9x but that one is good. Just a bit more heat so watch your temps regardless.

However, having said that, I underspin my alt with a 3.5" (for a 6#) lower instead of the 3.2" that keeps the alt near stock speed with a 2-4#.

Nice choice on the idlers but if you have the cash, go double bearing. Get the four piece, you want the snub idler and that's it!

You are correct I forgot to mention the 4lb lower I have..