me and my mates have done it in the past but not worth it!!

Unless your running big spec and need very good boost control you dont really need it, cheapest and pikeyest way for you doing it would be to take the actuator off, buy a 5 bolt universal flange off ebay for £12, make up a down pipe ( this will block up where your wastegate flap was) Then either get a stainless manifold you can weld a 38+mm fitting to for your wastegate, Or if you can, get someone to weld a mind steel flange for your wastegate onto your standard manifold, alot of fapping about just for a screamer pipe imo...

On my starlet i did the same as above and the car came on boost alot stronger than it did