Stock OEM Turbos Keep or Replace
 

I have read the FAQ's and searched the fourm have not found my answer yet? What is the max WHP I can produce with these things on pump gas. Can I replace them with turbos that will spool faster and produce more hp(ball bearing?) Do I need bigger intake, cooler, exhaust, and a chip to make them be more efficient. I get that bigger sometimes means more lag and I don,t want that. I want this car to be fun and dependable. Any ideas?

You dont need a bigger intake it wil work fine with oem twins and with a bigger turbo.I stil got my oem intake on
The oem cooler is also fine.also stil using my oem one
For the exhaust you can go 3'

What is the spec of the pump gas where you live? A BPU Mkiv TT won't do more than about 350rwhp on pump gas. Have you considered meth injection?
NO. Pick one - faster spooling or more hp. You can't have both. It's simple physics - a bigger, heavier turbine+compressor wheels take more energy to spool up. Can I eat more, exercise less and lose weight? Silly question, right? Yours is just as silly. Sorry just being honest. Newer technology turbos make a small % difference, but the general answer to your question is still pretty much a flat NO.
No, but all that stuff will help you to make more power with race fuel (or meth injection) and higher boost levels.
Lag is easy to deal with if you have a 6spd - just downshift! With an auto, it's a bit tougher - you need a high-stall torque converter. Either way, lag is overrated. Get a bigger single turbo and you won't regret it.