to check the exhaust leak on accordion connector. Can I do this by visual test only? or do I need to apply soapy water and see if it bubbles? or actually take it out and blow on it to see if it leaks ? or use flash light to see if any gas comes out while running the engine? what are the chance of the exhaust header actually have hole or crack? and what if turbo is shot? should I rebuild it or just buy new one thats maybe in bigger size? will bigger turbo need new computer tuning?