[luna-c]

I’m thinking of tuning my 1M. Currently completely stock.
I’m looking for a strong and practical set up – something that will retain the reliability and drivability of the standard car but make it even more fun to drive when you do want to put your foot down.

I can see 2 different set ups :
ECU remap / catless down pipes / uprated intercooler (primary cat bypass)
or
ECU remap / N55 mid pipes / uprated intercooler (secondary cat bypass).

I purposefully do not want to change the rear muffler as outwardly I would like to keep a stock appearance.

Re. ECU remap – who does the forum recommend : Evolve / DMS / Dinan………………..? Clearly for me this needs to be the most reputable company.

Evolve opts for the primary cat bypass and DMS for the secondary and from what I can see (from reading articles in BMW Car magazine) both achieve the same power/torque gains (430bhp/475lb-ft).

Personally I would have thought the Evolve route (changing the down pipes) would have released more power as the primary cats are the most restrictive.

I’ve heard, though, that changing the down pipes alters the car’s characteristics / power delivery - reducing low down torque and instead increasing the top end. Also, that it’s too noisy (not in a good way).

I’m looking for a fast road rather than track set up so if the above has any truth perhaps the N55 mid pipes are the better option. Low end torque must be more beneficial on the road.

Your thoughts on all the above points are most welcome.

How about passing the UK MOT. I believe as long as the primary or secondary cats stay in place the car will pass the emissions test. HOWEVER, I have seen in the MOT manual 2012 onwards it states : ‘a catalytic converter missing where one was fitted as standard’ is a reason for rejection.

Has anybody had a bad MOT experience? Clearly swapping down pipes at MOT time is an expensive affair and not something I intend on doing. N55 mid pipes clearly much easier to replace for MOT purposes if necessary.

Has anybody had issues with BMW at service time with their modified cars?
My heart seems to be telling me to go the Evolve catless down pipe route but my head seems to be pushing me in the direction of DMS and replacing the mid pipes (due to the catless down pipes possible reduction in low end torque / possible MOT issues / cost of returning to stock when the time has come to sell the 1M).

Again, your thoughts / views / opinions on all these related topics are most welcome. Thank you very much for taking the time to read this post!