My birthday is coming up on the 25th and i know what i want for it. I am planning on getting a cheap ebay dc style header, a high flow cat and having a muffler shop make me an exhaust. I was wondering what size exhaust a prelude has stock. I was thinking of having a muffler shop make me an exhaust made of 2.5 inch mandrel bent piping to my muffler (i already have it). Now is 2.5 too big? i have heard yes and no and i just want to hear from all you fellow luders out there...

 

This has been covered before, but the stock piping is about 2".

 

So the stock piping for the exhaust is 2inches X 2 inches???

 

ebay dc header is waste of money and 2,5" is not too big

 

If your having a muffler shop build you an exhaust and you already have the muffler then I'd say go with the 2.5" piping, espeically if the muffler has a 2.5" inlet and outlet. Definitely run the high flow cat and skip the headers. 2.5" piping isn't too big, it's just about right. If your motor is mainly stock than 2-1/4" -to- 2-3/4" is just about right. My Invidia N1 Stainless Cat-Back for my '01 Prelude Base is of the 60mm tubing or 2.36". I'd imagine they chose that size for a reason. The key is high flow while maintaining the right back-pressure in the system. You may want to consider the idea of whether or not to run a resonator. A resonator usually quiets down the sound a fair amount, but again, flow and back-pressure change as well. A high flow cat isn't gonna add 20hp but keeping a cat is a good idea for the earth, emissions and the fact that no cat would set off a check engine light, so for the money, going high flow is a good idea there. Headers, not worth the money in your case. The only time headers are necessary are when you are building a naturally aspirated engine for peak power and money is no concern. It takes a very well designed, high end header to make any kind of power and cheap eBay headers are not gonna be worth it. Don't get me wrong, on a $12k N/A build, with computer aided design and testing, you can build a $1,000 set of headers and add like maybe 15-20hp IF TUNED. I had a set of actual DC Sports headers on my f22b1 in my '94 Accord and they cracked along the welds like a mother f'er, on at least 3 separate occasions. Good fabrication costs good money,

You may not want to hear it but its worth saying, you may want to consider just buying an aftermarket stainless cat-back designed for your car, maybe even a used system if your tight on cash. If you already have a muffler, maybe you could sell it. Having a muffler shop mandrel bend, weld and fit a complete custom system isn't a bad idea, its actually kind of cool and I might do the same, it's like getting a chance to have something built from your taste, specs & under your terms but I'm just sayin for the $, you might end up spending more having the shop build it, but if thats alright with you then, hey