Hello. Im really new on setting up my ek sedan 97 civic. Im planning to install 4-2-1 headers and a custom 2.5in midpipe no resonator to a stock muffler from a dohc Si-R. Im customizing the sir muffler inlet to 2.5in as well. Will it affect the engine performance positively even a slight power to add up? I dont like those noisy aftermarket muffler as i only want mine lowkey.