ok here is the deal ive had my sr in my s14
(redtop) for about a year, well i was driving home and i hit about 8-9 psi of boost and i heard i think my bov sound off then the car started sputtering, its smoking a bit now at idel and (black smoke) which is fuel, the car starts up and idels but seems to me that the throttle response has gone to crap, im still able to hit boost just that i have to give it more throttle. the vac was low before around 9.5inv. - 9inv. when i started the car up again (letting it cool for about 45min to 1 hr.) it was displaing 7.5inv. but went back up to its normal level. i checked all the fluids and everything seems to be ok. also i didnt see any types of leakes or heard anything knocking or pinging. i was thinking maybe its the sparkplugs ( ngk iridiums 6 mos. old), coilpacks (about a year old also nissan factory bought brand new), or the turbo is shot. so please help me out with this problem cuase i dont have a clue.

 

i would say its a vaccum leak. i know you said you didnt hear any leaks, but check everything. soapy water and a spray bottle.

if you have a vaccum leak your car will sputter and not run good at all.

 

I had a problem a few weeks ago that sounds the same. It turned out that my Apex-i bov was stuck partly open. If you have an aftermarket bov it mught be worth your time to check it out