hello i have a 2009 mini cooper s (r56) so i have a cnt down pipe(catless) i have stock exhaust second cat removed and put back togher with jmtc turbo and ecu tuning rough guess id say im pushing 250hp with all that i have done have 44mm turbo on it and my question is car has been perefect then all of sudden i lost boost and car was fine no big deal then as it progressed in days to come i i am currently running and having very very very poor performance i have the torque app and i can wattch the car loose boost from 20 pounds - 18 - 15- to no boost i drive and smash it and runs some what good then i will loose boost and the sounds the car make from the turbo sounds like a woooooshing wosh wosh wosh wosh sounds when accelerating from 2 3 and 4th sorry if this is hard to understand and i explain like a 4 year old just loosing boost at high and low rpms not hitting as hard no where near and as the woosh sounds does the noise i every 1 second or so i will loose power any ideas?

(i can loose boost at 2k rpm 5k rpm dosnt matter rpms car could sit all day and night and get in and boom smash it some pulls are good first 2 3 boom no boost some pullls are straight crap and some are pretty good just not full power ))

 

Plug in to see if scanner tells you anything.
Check for boost leak through your charged section of all intake piping.
Check compression in each cylinder.
Get a readout for your fuel rail pressure. Should be above 740psi or above.
Check your vacuum lines to and from the turbo (both diverter valve and wastegate actuator connections) If your wastegate actuator ceased to work, it won't give you any boost at all.
I don't think this would be the case, but may consider taking out the downpipe and check the wastegate flapper. Make sure it seats properly and that the actuating rod is properly connected.

 

so everything u have told me i have checked even sent turbo back due to bad waste gate so a month after car runs perfect for about 10 days and now im having some what hard pulls and some super **** pulls stock bov but i have done all of that more i read and people tell me they say i have a leak somewhere idk what to think because car was perfect and then all of sudden **** i do have a stock exhaust and some people say the car is needing the exhuast and i agree but then i think well i went for 10 days and then all of sudden the car need pipes? im just at my whits end then i talk to others and they say its something super simple like a sensor and that all it is and i just need to keep replacing sensors till i find it

 

sorry for the language didn't no it would be blocked out my fault*