I am doing a s4 n/a to tii swap, and I was wondering if I need the knock box, the tii engine is to be slightly modified possibly around 280hp or so. I had read that it is relatively inefficient in the s4's.

 

Read the FAQ. The link in my sig will also take you to a detailed thread on TII swaps. You don't need the knock box, but you can add it in if you feel like making a little patch harness (with NA EM harness). If you're adapting a TII EM harness (harder), the box will plug in.

280whp is basically impossible with a stock turbo, so unless you're talking about a hybrid, it's out of the question. High boost with either stock turbo (S4 or S5) will not be very efficient, but it works. Intake temps will be higher than with a modern, more efficient turbo. And boost will drop off at higher RPMs, which is the reason it's difficult to make more than about ~250 whp.

 

Allright Thanks, i was looking at buying a T04B Turbocharger with a .60 AR Compressor and a 1.15 AR Turbine, along with doing a mild street port.