Front Pipe Install Gasket Issue?
 

Hello,

I recently got a MXP catless front pipe installed at a new mechanic as a lot of frs/brz guys in my area recommended him. In the instructions, it says to reuse the oem donut gasket but the new mechanic said that they used a flat head gasket instead as the fitment is better? Does anyone know if its fine or should I go back to my old mechanic to get him to put in the donut gasket? He said it was fine and they didn't find any leaks but will I run into any problems in the future?

i would use new donut gasket.

donut gasket

i reused mine from the stock FP, no leaks

What should I listen for if theres an exhaust leak? So far, I haven't noticed any issues with it and ive driven about 100km

Also, on the rare occasion when I tap the gas, I hear a faint wining sound but not sure if thats the drop in filter or exhaust. It happened before I got my front pipe installed too.

normally what i do, ill make sure the car is cool before starting it.

but just start the car, and rub your hands around the area you think you have an exhaust leak, if you feel anything, than you have a leak

From what I have seen on after market catback systems is if the midpipe has a flex joint, the supplied gasket will be a flat type. If there is no flex joint in the midpipe (as is the case on the stock midpipe) a donut gasket is used. Either way, I personally would want some kind of device that allowed the header and front pipe to move independently from the midpipe.

As for your wining sound you will have to provide a lot more information or a video of the problem for us to figure out what it is.