I found a person who is selling a Vortech S trim sq and it has about 15,000 miles on it. Can anyone tell me what I need to look for (impeller wobble etc.) to make sure the unit is good or is working properly. I have 30 lb injectors and steeda underdrive pullies. Do I need to get bigger injectors or change my underdrive pullies back to stock? Any help would be greatly appreciated.