A simple search would have prevented this worthless post. Want kindness?
There is a search feature on this site sir, it's a great tool to solving your questions. Questions like these (how fast will i be) are to hard to answer as there are way to many variables to take into consideration. t3t4 is a generic term for a hybrid turbo, you could be running a small t3t4 turbo or a very large t3t4 turbo. Without knowing the trim or A/R of the turbo it's hard to tell what kind of power potential there is. Also the amount of power and engine makes is greatly dependent upon the quality of the tune. Not all tuners are the same. Ive seen some awesome dyno charts of stock b18's making sick power on 10psi, only to have a better tuner retune the car and pick up even more power.
Also larger turbo's create peakier power bands thus (depending on how large) making less usable power, but high peak numbers. A broader power band will be faster then a peaky short power band.
Then you have to consider the drivers ability. Some people are awesome drivers and can pull some amazing times with little power, while other (we'll call them sucky) drivers don't know what they are doing and probably couldn't run faster then mid 14's in a car that has 400whp and weighs 2000lbs. It takes skill and knowledge to be able to race..it's not just mash the peddle and go.

Stock internals will be fine because I doubt he's going to be exceeding 300whp with only 8psi. Stock b-series (search would have told you this too) can handle about 300whp safely, i've seen some make 320whp or so and do just fine, it's ALL in the tuning....

So now that we've realized that you need to know a lot more info then you have provided...do you understand why posts like this get old? Nothing personal towards you, but there is no magic equation to figuring this stuf out...
The reason I said a search would have helped you greatly is because this type of topic has been covered so many times before.....it probably would have prevented you from posting this.