Slicks,sub 12 second runs,worries,questions,so-so answers...............
If it were me,Id just install an 8.8" and be done with it.
Why even chance it when 8.8" Fords are a dime a dozen,plenty strong,have lots of aftermarket support and are relatively easy to install?

 

I agree.. Get the 8.8 rear. I dynoed 414 RWHP on a 114 deg day. Going back for re-tune when Steve Kan comes to Vegas and will turn the boost up for more power.. I'm doing a 8.8 rear. I'm running a stock gsl-se rear right now but will not run my car with slicks. Don't trust the stock rear. Once the 8.8 is in I'll run a 10 sec pass...

 

But none of you are tracking your cars. You're all speculating at this point. I'm going to see what my factory rear will do. I was limited to 305@9-10psi on my last tune due to bad break up. After a little tweaking, i've gotten the car to trap 117 on 9-10psi. After i get agressive with boost, i wanna see what the car will do on an et drag, and see what the factory rear will take. Guys on TC are going 10's on them, but most are using auto's, and not launching at 7500.

 

True,my car is not a regular track vehicle.
I have made a couple dozen passes down the track,and I usually launched around 3-4K RPMS.My engine makes around 300HP,but has a bit of lag,so theres no punishing lowend torque to break things,and I dont run slicks.5 years of daily street driving doesnt really prove anything since I drive pretty relaxed and I almost never abuse my car.

Really,the only way you can prove anything and provide anything more than speculation,is to try it yourself.Just cause one shop has done it,doesnt mean its an all encompassing truth.Plenty of guys here have blown up stock rearends with an anemic 100HP 12A,it has a lot to do with technique,carelessness and/or ignorance.
Experiencing a rearend failure can be costly and dangerous to you,others and the rest of the powerplant.If your worried the rearend wont hold up,then youll alter your driving/launching habits,and that will usually mean that you arent racing to your car's full potential......which of course is what competition racing is all about.Build it to take anything you can dish out, within expected conditions,without being too heavy,and youll have one less thing holding you back from being as quick as is possible.

Id be willing to bet the housing and 3rd are capable of holding quite a lot of torque.Its the axles that are painfully small, and they receive the highest torque loading of all the drivetrain parts.

 

8.8's are an extra 80lbs of ****... not my cup of tea. I'll let you know how my factory rear holds up. If I do anyting it'lll be mosler axles.