I guess question was garret vs PTE .63 housing.I've seen both and the PTE looks like a ported/flowed housing.And would lend itself to a horsepower inprovement.
The big deal on the exhuast housings is this....the size of the puck hole.If you run an external wastegate the hole will be approx 1.5 inches in diameter.If you run a stock elbow..about an inch and a THDP 1.25 inches.
So if you get a PTE exhuast housing thats got a stock 1 inch hole..no problem with any downpipe/wastegate scenarios..if you get one with the 1 1/2 hole..then can only use an external wastegate.And once the whole is opened up...cant go smaller.
Now whats getting hard to find are flat,straight,unmodified,no stripped holes, garret .63 housings....but who care's unless your restoring.
HTH