i got a new DC Sport header in the other day and i havent put it on yet but ive been looking at it some and im not sure if the stock exhuast system will be able to meet up with the header b/c the 4-2-1 has a 2" outlet and idk if the stock system is the same, can i get some help before i got through all the work and find out it wont fit

 

If you bought the correct header for your application then it'll fit. The smaller diameter exhaust piping will prevent you from getting much if any better performance, depending on how it's handled. A smooth size reduction won't create the turbulence problem associated with connecting a smaller pipe onto a larger one, which can actually decrease top-end flow. Of course, if you're going to weld on a reducer segment then you should just run larger pipe.

 

depending on what manifold he has now, he may notice some increased midrange power. I do agree, you should upgrade to about 2 to 2.5 inch depending on what motor you have and power goals.

 

what's the product # for the header you bought. it should be on the top of the instructions paper. mine's HHC5604 http://www.summitracing.com/parts.aspx?sku=DCS-HHC5604 for my 00 em1

i bought mine simply to replace the stock manifold because the entire exhaust was rotted. honda wants too much for a stock manifold, so this was my only option, (aside from getting an oe replacement, but it got a great deal on the header).

i'm in the same predicament as you. i haven't installed it yet, still waiting on the rest of the exhaust to arrive, but the magnaflow stock replacement cat i got doesn't look like it matches up with the header. i guess when i'm ready to put it all together i'll find out. but if it doesn't fit right i'm screwed. the old exhaust is in such bad shape that i'm anticipating having to cut half of it off the car, so i won't be able to get it back on.

 

not to try and steal the thread but i thought i would just ask my simple question in here without making a whole new thread. im running 2.5"piping from the cat back, to a stock muffler. well gonna be finishing it hopefully today if i ever get the call to weld the last spot in. but besides that i was wondering what i should expect with the fact the center pipe is 2.5" and im pretty sure header coming down is the same. but what should i expect from that decrease in piping size.

 

http://www.summitracing.com/parts/DCS-HHC5013/
thats the header i got, and i have a D16Y7 that im putting it on, and pretty much the only reason why im getting this header is because my current exhaust manifold is cracked and i dont want to pay Honda $600 for a new manifold. So lets just say that the header collector is bigger then the pipe what can i do?