when im accelerating my car as trouble building boost at 1 pound and 5 pounds. if i put my foot into it. it lags a little. but it builds boost perfect right to 15 pounds. sometimes it doesnt get to 15 it may stop at 12 pounds. I have a walbro255 and ams FPR drop in k&n and the car is untuned.?

 

boost leak/get tuned.

 

sounds like a really bad boost leak. Check that intercooler piping!

 

is it kinda bogging down? or not going over 4K rpm? if yes, check your spark plugs, mine did that and i had a spark plug that was burned out.

 

sounds like a boost leak and you are on wastegate pressure.

 

What form of boost control are you using? Do a boost leak test. If there's no boost leaks check your snorkel on the intake box. Make sure it's fastened down with the 2 push in screws in the front. If that's fine check your cat. When my cat went out it caused a clog in my exhaust and really choked the turbo. I couldn't boost past 11 psi. Check those items first then report back haha. Do it in this order though
1.check snorkel
2.boost leak test
3.check cat

To be clear, by snorkel I mean the ram air scoop that slides into the intake box at the top and feeds air from the front.

 

I bought new plugs off lancershop should be here soon. all the pipes need to be checked?

 

^ You need to perform a proper boost leak test on your car.

 

Why did you buy new plugs without checking the things I recommended first? You might have just wasted money. Might have been better to spend that money on making a boost leak tester or purchasing one. Check the 3 things I told you as those could be the cause and easy to fix and most important, FREE to fix. Check them and we can go from there.

 

I had the snorkel problem I would build about 10-15psi, and then when I would get up to about 30mph the snorkel would suck itself into the hood causing boost to instantly drop to 5psi.