Do you have to tune/retune for an UDP? I'm installing some LT's, so if my UDP comes in with the necessary parts, do I need to tune it along with the headers?

You don't need to tune for the UDP. It won't change the A/F ratio.

Not for the pulley alone. But with the headers it would make sense. And since you ought to get a tune. Here is what I'd have the tuner do.

Raise "in drive" idle speed by 50rpms (all the time)
Raise "neutral" ilde speed by 100rpms (all the time)
Add 50rpms to "ac on when in neutral" (this is additive to the 100rpms)

That way your ac compressor speed is running good when in N or P.
And the added 50rpm when in drive will help ac, ps, cooling, and volts a little w/o you really feeling the car pulling more when stopped and in gear.

Rich

You don't need to tune for the UDP. It won't change the A/F ratio.

Correct.

Not for the pulley alone. But with the headers it would make sense. And since you ought to get a tune. Here is what I'd have the tuner do.

Raise "in drive" idle speed by 50rpms (all the time)
Raise "neutral" ilde speed by 100rpms (all the time)
Add 50rpms to "ac on when in neutral" (this is additive to the 100rpms)

That way your ac compressor speed is running good when in N or P.
And the added 50rpm when in drive will help ac, ps, cooling, and volts a little w/o you really feeling the car pulling more when stopped and in gear.

Rich

I raised idle to 625rpm to help PS and Charging. A/C pulley is not underdriven.

A/C pulley is not underdriven.

Can you tell I don't have a G8 yet? :popcorn2: