i have a stock exhaust system right now im planning on getting a magnaflow catback im still saving for it but i was thinkin to change the down pipe for now is this ok and how much power will this give me and also will changing the down pipe on my 06 void my warranty for anything?

First the warranty thing:

Probably,so be ready to re-install the stock D/P,if you need any serious warranty work.

Second:

I doubt the Magnaflow exhaust will do much for you,unless your car is heavily modified - probably not modified if you're concerned about a warrany.
I did the SPO tips and noticed a slight difference in power as well as a nice change in exhaust note.
Look at the design of the stock tips vs. the SPO's.
You'll see why.

The best bang for the buck seems to be enhancing the front section of the exhaust.
On my car I have thermal coated PEM's and a ZZP 2.5" stainless D/P with a Magnaflow 99306HM CARB approved CAT.
The CAT supplied with the ZZP D/P threw a code with the suplied CAT.
I had to have the supplied CAT replaced with the new Magnaflow to shut off the check engine light.
No more problems and I'll let you know how it does on our California style E-Test later this week.

If I had to do it again,I would buy the D/P with a Random Tech CAT installed or buy the D/P without the CAT [O2 bungs installed] and weld in a good CAT afterwards.
Get the gaskets and and O2 extension harness and you're good to go.

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2005 GT owner [Non S/C] with a "big DIC".
Two years later and I still love the car.
Thanks Pontiac...Bleen is keen!

yeh cant really do much cause of the warranty im just trying to do the basics rights now but thanks for the help you have a nice set up tho ill look into that for sure

You could get away with uncoated PEM's to start and go from there.

_________________
2005 GT owner [Non S/C] with a "big DIC".
Two years later and I still love the car.
Thanks Pontiac...Bleen is keen!

Exhaust shouldn't void your warranty... Its a "maintenance" item and you're replacing it with parts comparable with stock...

If you're worried about the warranty just make sure you have a cat a resonator and two mufflers and you should never have any issues with a dealership.

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yep thats tru i dont plan on taking any of those off i plan on changing them tho thats about it lol