guts311

I have a 94 ex coupe with a frankenstein Si head on a gs-r block, and when i start my car and let it idle for a bit, the exhaust will make a few short barely noticeable sputtering noises, same as the engine...the rpms stay around 900-1100 all the time which sounds normal but it just sounds like small twitching engine and exhaust noises..like if u stand near the car or behind it...nothing too noticeable though...and the car drives great, no problems...so why might the idle be like this and the car be making "back-firing" type noises every so often at idle?