I drive my car everyday and currently have Mugen header and Invidia Exhaust. I just bought a test pipe in preperation for cams becuase i have herd of problems with cat becuase of fuel mixture. But either way, I would like to get the Mugen exhasut here soon but it will be a while as more items are on priority i was thinking of running my stock cat back with the test pipe and header. Whsat will it sound like shit ??? or ok. Also I do not thinking i will be giving up any power as aftermaket exhaust usually dont gain much if any power. could anyone please help me here.

 

A testpipe combined with the invidia tends to knock the drone out a bit. However, your car will be A LOT LOUDER than before.

The stock cat. flows very well as it is.

 

I think a better choice would be to go with a Toda header instead of your Mugen piece if you're planning on going with a straight pipe. The Mugen header doesn't provide the kind of gains you'd see using the Toda, however all that increased airflow from your Mugen intake, header, straight pipe and exhaust will mean your AF will lean out a bit (not much of an issue on the OEM ECU), but will be a concern if you're using a Mugen N1 ECU.

 

What about with stock exhaust cause I plan on gettting the Mugen Exhasut here in a few months and there is no HP gain over stock so what if I run that untill i get the Mugen. Will it sound like a Civic with header on stock exahsut cause I have hered a DX with that and it sounded like ass.

 

stock exhaust is pretty good as is, and as quiet as they come. The Mugen exhaust flows a little better than OEM, and has a few HP to gain... but the primary benefit is the weight reduction AND it's the most quiet aftermarket exhaust out there.

 

I doubt the Mugen header makes a difference in the sound of the exhuast. If you put the stock exhaust back on with the test pipe, it will sound fine (that is the way mine is). It is a little louder than stock, but it sounds about the same.