I can easily buy an apexi n1 universal which has a 2.5" inlet ,what size is the stock exhaust pipe i will have to weld too,and is it worth the effort to weld or just get a full CATBACK SYSTEM? oh and yes i am a newbie cuz i havent done any exhaust systems on my car at all!

 

Go full catback.

Stock piping is like 1.75 inches, or something like that, its tiny.

Get 2.5 all the way back. Remove cat or by a high flow cat.

Just have a muffler shop bend the piping you need, and buy a muffler. Much cheaper than buying a complete catback exhaust. I would never pay like $500 for that ****!!

IF your worried about the muffler shop using crush bends instead of mandrel, buy some mandrel bends from JCWhitney.com and have him use those instead.

 

one thing to remember., when you buy a complete catback for $x00 your most likely getting stainless steel. Which is going to last a hell of alot longer then the pipe you'll get at an exhaust shop

 

Actually the stock exhaust size is 1.5 inch(very small) if you plan on going super charged or turbo i would go with a 2.5 inch. If your going all motor i would stick with somthing like 2.0 or 2.25 inch.

Either way i have the n1 exhaust with silencer it sounds awesome I do reccomend a high flow cat and header with this setup.

As far as getting a custom exhaust or getting stainless steal i would go with custom thru a muffler shop, hope i helped

 

2.5 inch pipe on a NA four cylinder is ridiculously large.

I'm all for custom bent exhausts. The power difference between a custom exhaust and an off-the-shelf exhaust is small or nonexistant. Not to mention that all the aftermarket cat backs are much too large and put the power band up too high. I have to get custom bent because that is the only way to get 2inch ID which I know to be the best diameter for this size engine. Also, it sounds amazing. Very unlike your average modified Civic.

Get a Magnaflow muffler online, I've seen them for less than $80 depending on whether you want shiny or aluminum. I got a 14inch oval. The bigger, the quieter. If you want mandrel bends, get under the car and figure out what angles you need, then order them from JC Whitney. But really that's going overboard. Take that to a muffler shop and have them do a cat back, labor should be less than $60. If your engine is under 2 liters and driven primarily on the street or autoX (which is 0-40mph anyway), go with 2 inches ID. It will give you gains all throughout the powerband unlike a large exhaust which will hurt your low end but give you big gains up high. 2.5 sounds like crap and makes the car feel slower. Unless you're FI or like to hit 10,000 RPM all the time. The pipe will outlast your car unless you live in the snow or on the beach or something.