fuel pump for juiced 2007

hi, which fuel pump can i use to upgrade the stock one? (not Shelby kit, no budget for that) just to replace the pump only i'm using ZEX 175 shot of nitrous on a stock 2007 and i keep blowing the plugs beacuse i'm leaning out in fourth gear (on th wide band i see A/F through all rpm range in third gear and its Ok 11.8 but when i'm reaching 6k on fourth gear it starts to lean and my duty cycle on the pump is full (thats what i can see on the predator) ohh and almost always back fires when i'm shifting from third to fourth i have C&L CAI and the filter blew out i have to run without filter i don't know why!
The other question is wich plugs are good besides Autolite HTO for my aplication?

it blew up because of the backfire and now i use the CAI without the filter but i want to solve the problem!

hi, i have 175 because i called zex they told me that it was ok, i have custom tune for that, the injectors are not maxing out but the pump yes the fuel press drops after third gear the fuel filter is new, zex told me i need a better pump or a BAP and my engine is perfect!