gtfaded

On my way home from work today i was on the highway and went to 4th gear to get around a car and during acceleration it stops pulling. Drove it the rest of the way home and deffinatly felt like the turbo wasnt spooling, or no boost. if i floor it in any gear at any rpm you can tell easily. it makes a rattling sound sounds like from downpipe or upipe entrance. What could have happened, i thought maybe exhaust leak, wastegate stuck or something but i DO hear the spool but no acceleration. Was going to drive again after cooling down to better examine the problem. Anything sound familiar?
Mods -
upipe
downpipe
full borla hush exhaust
k&n drop in filter
re flashed vishnu tuned ecu
UPDATE* so i just drove the car after cooling for about 2 hours and it now has normal boost at 3-3300 rpm BUT stops boosting at 41-4300 rpm and kinda seems like it holds that boost while the rpm increases but it is apparent that its being held back, kinda like a N/A car would respond at that rpm, hard to describe but anyway i dont have a boost gauge, iknow iknow, but i can deffinatly tell normal boost from abnormal boost and acceleration. Any ideas?
i think ill have to break down and take it somewhere, it seems the problems not so apparent in lower gears but it's really noticable in 4th and 5th.