M50 non Vanos E36

Hey I have a question, I have a Non-Vanos M50 2.5L I was curious if I was to install the M3 TB & Intake if it would actually help or hinder the performance of the engine? As it is I have recived mixxed opionions. One person says yes it will give me upwards or 10 to 15hp and another shop says no the other guy is wrong and knows nothing you will actually loose better than 15hp. I am really lost here I have both units but I do not feel like installing them if they are not worth it. has anyone actually done this or had any experience doing it??

My mods are very minimul, as all I have done is as follows.

I have a brand new, hand built M50 Non-Vanos. 2.5L with M3 Headers, Mid Pipe & Rear Exhaust Section, ODB1 Conversion & I am running a GIAC stage two chip, Ported Head, New Valves with a swirl grind, (i forget the size but they are the smaller ones... 7mm???)The block had 20,000miles But we rebuilt it as well. I also have a new 330 tranny, and a limited slip rear end.

I would like to either super charge or turbo my car but that is if I can save the cash to do it right now I am undecided on whether to keep my car and buy a newer 330 as I will spend more upgrading my car than actually buying a new one and I really love the looks of the new E46. If I do keep mine I want to do a E36/46 Conversion but that is another thing to think about. But if you can help me out with this as I do not have the cash to buy a new one now so please let me know thanks!!!!!!

built up motor + turbo = you'll love it , i know i would if i had tha cash ;) , but really man get the engine built and get a turbo kit or get a custom fabricated one somehow because and active autowerks turbo kit stage 2 costs fuken 10 gs !!!!