What launch rpm?
 

With my current mods what rpm should i be launching from with prostars oon the back and mt dr's with street tires on 18's up front? Also what psi do i put the dr's to ?

There is no set launch RPM. It will vary depending on temperature, track conditions, driving skills, mods, weight, etc. etc. Best thing to do is go out and test it yourself. Should be over 3800 though. You want to run the highest PSI you can while still getting traction. As low PSI will slow the car down.

im going to try 3k with my automatic when i get home. Would you say launching with a auto or manual is better/easier?

So you have a built rear and spec clutch and sticky tires, its time to go big and launch hard. I would go 5,000rpms with that setup and see how it hooks up. But like he said it depends on alot of things.

what constitutes a "built rear end"?

Hes got 31spline axles,31spline posi, so its built. The aftermarket 31spline axles are alot stronger then stock.

I have absolutely no clue what psi to put these tires?!?! Im goin to try to launch @ 4k-5k rpms but i need to know ho to use these tires properly i've never used anything except street tires. How long do i burn em etc? I'm really confused. The tires measure 15" 275" width and i believe they are either 27" or 28" tall. Help me out what psi? I live in Austin/San Antonio.

try 20 psi heat them for 3-5 seconds. stay out of the water box since you have radials.

hold the rpms at 4500-5k and side step it.

I hope they arent 27" or 28" tall. Thats way too tall of a tire for your set up.

I would start at like 18psi and work my way down to what ever works best. I would rev to 5k and not side step it as you have a stock tranny i belive so just let the clutch out fast without popping it so you dont break the input shaft on your 3650 tranny.

With any racing tire go around the water box back in and get both back tires wet pull forward out of the water a few feet and smoke them up. You will have to see how much heat works best for you some just smoke till they see smoke some wait for smoke and count to 5 etc... you will have to pratice and see what works. But be sure to not drive threw that drags water up to the starting line because your front tires will be covered and this will make you and others spin and makes us ALL ANGRY.

The tire i svery tall and does fit but it's pretty tight but i don't think i will rub as i have an airbag in my right rear spring.

best for me in '06 GT automatic
 

I stage very shallow, what I mean by that is I creep slowly until the second staging light comes on, I go no further then I stand on the brake!, bring the R's up to 2k, when the 3rd light comes on I nail it. I have 275-40's which bit e pretty good, launching at 2k gives me enough spin so the car doesn't bog. I have an Airaid CAI and 4:10's. I run consistantly high 8.60's/ low 8.70's in 100 degree and 85% humidity.

In the cooler months you can knock .5 or my 1/8 mile ET's. yes it makes that much difference