Im about to do a lsvtec on my 94 rs. Engine will be 100% stock for now. I am wondering which ecu I should be running some people told me I could run the stock ls ecu and others told me to get a chipped P28 chipped for all motor. For the P28 should I just buy a pre chipped one off of ebay and bring it to the shop and have them tune then ecu for my setup?