I'm getting my 06 GT this weekend and I have like 1500-2000 for mods. I definetly am going with the C&L CAI, SCT2 tune, and axle back exhaust. I have been reading about the Steeda Underdrive Pullies and it claims to add 8-10 hp using the factory belt. How exactly does this work? Is it worth the $200? Thanks for any input.

 

The pulleys are a different size from the factory pulleys. By changing size, you change the speed of which the accessories turn, thus reducing the parasitic loss caused by driving those accessories.

And yes, they are a worthy purchase.

 

Is that something that requires a retune because they are a different size?

 

Nope. Only time you are going to need a retune is if you change something that effects fuel intake, air intake, or exhaust output.(not including speedo recalibration for gear change)
Pulleys do not affect any of those.

 

If the accessories are turning slower, wouldn't that adversely affect their designed performance parameters...like how the alternator charges? Or is there enough of a performance envelope as to not make a negative impact on the accessory?

 

If you sit in traffic for long periods of time on a July day in Arizona ( or Texas, or New Mexico or..well, you get my point ) with the A/C on, yes, you are going to notice at idle that the A/C isn't as cold. Same goes for a bazillion watt stereo, you are going to notice that your battery is discharging. But, by the same right, the alternator is designed to supply maxium output with the motor at only 2000 RPM. So, yes, in adverse situations you can ( and will ) see an affect to those components. But then again under normal every day situations that never comes in to play.

Just as a FYI, I had Steeda UDPs on my car, and live in Texas. Trust me, it gets hot here. I have 1500w of stereo with multiple amps, and I like my A/C. Drove the car most every day last summer to and from work. Not once did I ever notice that it changed the way anything operated.

 

www.brenspeed.com has them on sale for 205 /shipping handling free!

 

I am really tempted to order the Steeda Underdrive Pullies tonight. Install time/cost?

 

Install time is about an hour on average. Cost, nothing if you do it yourself, or whater the hourly rate is for the shop you choose.
Without pnumatic tools it is a little tricky to get the crank bolt loose, but that is about the only part of it that is hard. And even with that it can be done in your garage/driveway.

 

Cool. Thanks for the info hawgman.