i did yeh when the pipes were off, seems fine not much play and wastegate isnt stuck.
 
i figure it is something electronic or a sensor because even if wastegate was stuck open and i had no boost that shouldnt stop the engine from revving like normal correct??
 
but have no idea where to start looking lol

Check your ignition components. Have a look at the dizzy cap and rotor.
How old are the plugs and plug wires?

Correct, you would just get a lower boost. but if the turbo shaft itself is stuck it would create a massive restriction in your intake (and exhaust).  You should check it, but strange it would **** it self all of a sudden.
 
When you drive it does it not rev beyond 4500 rpm at all, or is it just slow?
 
You could disconnect the intake pipe from the throttle body and see if that makes any difference to the way it drives, bypassing the turbo.  If not refit and take exhaust off and see if that does anything.  Maybe something disloged and has blocked the muffler? If both make no difference you know it fuel/ignition/electronics, nothing else it could be really.
 
You havent got water in the spark plug holes or anything like that?  What do the plug look like?
 
Strange that the issue appeared after you changed the exhaust.  Just methodically go through each bit step by step.
 
Cheers

plugs and wires are brand new, havent done cap and rotor since i got the car, might have to give them a go.
 
yeh it revs past 4500 but gets slower and slower and it sounds like its working really hard.
 
yeh wierd cause i had the exhaust on for a few days and it was fine then bam it went to ****.
 
ill try and source a new cap and rotor and see if that does it.

Ive got a similiar problem friday night i was driveing up n down giveing it no problems last night it started getting heavy while driveing on the freeway wouldnt let me rev after 3500rmp n if i pushed itll miss, ended up stoping at a carwash checked all my lines were fine hoses fine checked the dizzy was a little loose but not loose enough to turn i gave up cuz it was getting late jumped in the car and drove fine?¿ untill now no issues i have checked almost everyrhing now gotta do dizzy which i put on hold gotta pay for hope that fixs it, try the dizzy check timeing if that doesnt work then .... cuz i have been scratching my head for weeks now n cant find the problem lol

I would also check to see if the turbo wheel has been rubbing on the comp cover and also check your vac / boost lines, like the map sensor lines and fuel pressure reg lines, 
 
Does your car have a ceramic turbo? if so it is also possible to snap a shaft, the front would spin freely but the turbine could be jammed also blocking the flow.
 
And check your cat converter, if you have the stock one they block up very easily, and that would also explain the lack of power and no boost due to the insane about of back pressure.
 
Last but not least do a compression test, if all your rings are gone then no compression > no load > no exhaust pressure > no boost. 
 
Is the car hard to start?

nope car starts and idles like a dream its only when i try and drive it, it revs better in neutral with no load but gets worse when im out on the road.
 
removed the factory dump pipe yesterday and replaced with Berk Dump so no factory cat anymore cause i thought thats what it might of been, but no such luck :(
 
havent done a compression test and yeh factory turbo so could be shaft anyway i can check that??

fixed!!!!! finally.
 
turns out the pins had come loose in the MAP sensor and werent connecting properly. >.<
 
 

Good it hear it was only something as simple as that!

ya very relieved lol
 
and i fixed the injector problem i was having so now it is running properly for the first time 3 months.... haha'
 
bloody good to have it back to running perfect again to.