JB/other tuned experience?

Hi guys! For those that have gone the JB route or other products, has anyone experienced any troubles afterwards like detonation or backfire or popped coils etc?

I've previously had a mk6gti, went the k04 route and eventually had so many issues that i sold the car!

The prices at JSN is a big NO NO, So considering a more wallet friendly approach

I've got a stock '13 M135i, looking at sw only at this stage ...

Any advice would be appreciated