e90 330d remap and exhaust help needed.

Hi Guys

I'm wanting to introduce myself as well as ask a question that ive been searching on the internet for but haven't found an exact answer for.

I just purchased a 2006 e90 330d with an m sport package which is an absolutely amazing car coming for a 1996 316i

I've been quoted to get my car chipped/ exhaust fitted at Steve's auto clinic.

1) my question is are they the best car chipping/ exhaust modifying company in the port Elizabeth area or are there better?

2) they quoted me another R3 500 for a free flow exhaust, decat and DPF removal, will their be any noticeable increase in power and if so any estimates or is it a waste of cash as I'm a bit tight after the car purchase or is it really worth it?

thanks so much for your help in advance and hoping to spend loads of time on this forum in the future!