Originally Posted by IancoleTX
With manifold, tune, and headers (probably $3-4k all in), you are looking at probably 290 at the crank, ~250whp. Stock 335s dyno 260-280whp, so we are still looking at about a 20whp deficit. We would have benefit of less weight (~200lb) and a more linear power curve. I think it would be close with a stock 335i. However, that leaves us maxed out for power, and at that point the 335 can add a chip for a few hundred bucks and forget about it.
All that money and still way down on torque compared to 335 and as you said they can put a juice box + or SSTT in for 100 - 200 dollars (used) and add 40 hp and 50 ft lbs. Just a little more $ and you can get a lot more HP and torque with a JB3 or procede.