Headers causing buzzing noise and check engine light ?

I recentlyl purchased some new DC SPORT 4-2-1 headers from a friend who used them on his SI for a year. I got them at good deal so I'm happy with them. My concern however is that in order to install the ehaders on my 98 DX I had to remove the cat. My car went from a 17.2 stock to a 16.6 with intake and exahust. Since installing my headers I've seemed to drop back into the 16.9-17.0 range...reaaaaaaaalllly slow!!!!! But what concerns me more is that when I hit 3000 rpm my exhaust makes this buzzing noise and it's pretty loud and it conituens until i hit about 3400 or 3500...in order to install the headers I had to use one 02 senosr and the other is tied to the engine bay. My check engine light oems on every now and then and I"m just curious as to what the noise is and how to fix it. Should I get an aftermarket cat or what ? Please help!!!!!

[ebpda9]

once is enough

[Addict]

You used Si(DOHC) headers on a DX? And they fit? Well part of your slowness has to do with header diameter. They were made for an Si. The DX headers are smaller in diameter.

My advice is to sell the headers on eBay and get the right set. Put your cat back on or get a new CATCO or Random Tech cat. That'll get rid of your CELs you keep getting and restore your power........

[slowEJ6]

B series header on a D series? uhhhh no.

16.6 w/ i/e? ouch. i hit 16.4 with just exhaust.

buzzing huh? something probably isnt bolted up correctly or is cracked.

[TonitrusEN]

4-2-1 headers are for D series engines... his friend had them on the wrong car

OR they arent 4-2-1 headers...and that would explain his car screwing up

[slowEJ6]

yes they make 4-2-1 for D series, i figured he meant 92-95 Si.

his car wouldnt be screwing up if they were 4-1.

[nonovurbizniz]

if you both added a header and removed the cat there is no way you should loose any time you should be gaining good time.

I'm gunna go with Civic_Addict sell them and get the right one for the application. but even if they have larger primaries you should be getting an increase in performance.

my bet is that the lack of the second O2 sensor is screwing up your computer's reading's and there for screwing up the fuel delivery.

[Kyle]

well, the check engine light is just your o2 sensor...go get another one from a honda dealer...
And I'm guessing the header doesn't fit or just isn't bolted on right...