Yes I agree with you that the throttle lag delay in the 550 (at least in mine) is maddening. It really does make me miss my E39 540 which had absolutely no such delay. To lessen the delay, I got the Sprintbooster. The SB does not eliminate the delay but it does lessen it -- at the expense of a jerky throttle response.

 

Manual transmission would fix any throttle lag

 

So does M mode. Its much more consistent even starting out in M2. If you want the power, start in M1. No lag there, you just have to be light with the throttle or DSC cuts in.

 

I am a Pakistani from Pakistan

 

How would the 550I do with the RPI bits, exhaust, scoops, and sprintbooster.

 

It is all about the driver when you're talking about streetlight races. I've beaten some seriously overpowered cars and been beaten by some severely underpowered ones way back when I used to get into this kind of things.

At the end of the day, the power-to-weight ratio in both - 550 and 535 is about the same, so acceleration should be near-identical in identical modes/stages of tune.

About the same

 

I would agree that from 0 to 60, where power to weight is king, the stock 535 and 550 should be neck and neck. But as speed increases, power to weight is overshadowed by the car's maximum horsepower, frontal area and drag coefficient -- some of the factors that determine top speed. For those reasons, as speeds increase to extra legal numbers, the 550 should be faster than the 535.

Of course, a 535 with a good tune should smoke a stock 550 as those tunes give the car over 400 bhp.