swapping DC 421 w/ A4 header

[91 EX-R]

Bisimoto headers are good, but WHEN are they gonna be available? people have been talking and talking and nothing yet. And I heard $600 floating around for the cost of it? too much for just a std. bolt on for me right now. besides i just want to get rid of that raspiness i have at a certain RPM.

Bisimoto's first header will be going to HondaFan for his white project.

and $600 isn't that bad. this will probably be the best header on the market for that price. and i'm pretty sure they're expecting something like an 8 horsepower gain at the wheels! try comparing that to other headers and you'll see what i mean.

[wrichards2005]

Bisimoto's first header will be going to HondaFan for his white project.

and $600 isn't that bad. this will probably be the best header on the market for that price. and i'm pretty sure they're expecting something like an 8 horsepower gain at the wheels! try comparing that to other headers and you'll see what i mean.

That definitely isn't bad. Especially when you compare the 250-350 price tag of a DC header that could potentially LOSE power compared to an A4 header. With an F series (A1, A4 and A6 only), I would take the power wherever I could get it.

[BB6-SH]

get a resonator to get rid of the raspiness, thats what i need to do. I don't think the a4 header is equivalent to a dc sports header. Look at the size

[rudy1980]

No i think you've got it flipped, i want to keep the DC downpipe but change the upper portion to the A4 manifold. I mistakenly threw out my A6 header and downpipe in the dumpster right after i got my new DC header...shoulda kept them.

Either way it still won't bolt up, there're different lengths. At least the A6 is I'm not sure about the A4.

[Losiracer2]

oh wow, i didn't think it was that big of a difference. I guess the DC really does make more power, when you put it that way. So where do people usually place the resonators? I just dont want to cut up the Greddy exhaust, but I guess it's unavoidable. Will any resonator do the job or are there better ones out there that i should look for?

[wed3k]

i got raspiness from my DC header...i guesss thats why i dont want to part from my a4 :o

[owequitit]

1) Who ever said that a DC Header loses compared to an A4 manifold?

Mine was worth a little increase in the top end. Everyone is so quick to bag on stuff they don't know. Keep in mind people, that if you were to just bolt a Bisimoto header on and got 8WHP, it isn't going to feel like a HUGE gigantic increase.

The DC routinely dynos 3-5WHP higher than the stock. Is it a great header with maximum R & D, no, but is it better than stock, in most cases.

A simple look at the collector is a good basis for comparison. I just measured these out. The other day. The stock collector has a .25-.5" smaller internal diameter. That will be good for at least some flow, even if the rest is equal to the stocker. The collectors are also a little smoother than stock, so I would expect some minor flow gains there too.

When coupled with a stock size high flow cat, the increase was noticable.

Losiracer, personally, if it were me, I would get rid of that test pipe and put your stock cat back on for now. Those are a huge source of raspiness.

Then I would consider a high flow cat. Magnaflow is cheap, but they too add a little raspiness compared to the stock cat. Apparently Catco sounds pretty good, but they are a little more spendy, so you will have to decide.

I haven't looked at the G'reddy EVO 2, but I can't imagine a quality exhaust system with no resonator...so I would check to make sure it doesn't have one already.

[Losiracer2]

hmmm yeah i just looked, it looks like my greddy system comes with a resonator already, its about 15 inches long. I've searched for about 10 min now, and all i can find when I type catco high flow is a direct OEM replacement converter. Also, what size is required for our cars? is it 13 in or 14 in? Where's the best place to get them at?

[owequitit]

hmmm yeah i just looked, it looks like my greddy system comes with a resonator already, its about 15 inches long. I've searched for about 10 min now, and all i can find when I type catco high flow is a direct OEM replacement converter. Also, what size is required for our cars? is it 13 in or 14 in? Where's the best place to get them at?

The catco will be a stock replacement. The stock inlet is about 2", but the collector on the exhaust manifold was smaller due to it being double walled, so it would retain heat better.

Summitracing.com would probably be a good place to get it. Fair price, good service, good stock, good reputation.

Also, I forgot to mention that my DC did create some raspiness when I installed it, but nowhere near what the cat did.

[Losiracer2]

The catco will be a stock replacement. The stock inlet is about 2", but the collector on the exhaust manifold was smaller due to it being double walled, so it would retain heat better.

Summitracing.com would probably be a good place to get it. Fair price, good service, good stock, good reputation.

Also, I forgot to mention that my DC did create some raspiness when I installed it, but nowhere near what the cat did.

so should i get a 2.5 inlet/outlet since i have an exhaust of 2.5 in and the header of 2.5 in?

[owequitit]

so should i get a 2.5 inlet/outlet since i have an exhaust of 2.5 in and the header of 2.5 in?

I am not sure if Catco offers that or not. Magnaflow may be the better option.

If you have a 2.5" exhaust, and can get a Catco in that size, that will fit your car, I would do that. Hondafan81 has one on his red project, and he said that it isn't raspy at all.

Of course, having just said that, I guess it answers the question about whether or not they make it. LOL! "Here's your sign..."

The stock cat length I believe is 13." so that would be the length you would need.

[TheNextEpisode]

so should i get a 2.5 inlet/outlet since i have an exhaust of 2.5 in and the header of 2.5 in?

I'm running a carsound cat and I'm relatively happy with it. I have no resonance, with a borla straight through and a flowmaster resonator. Also, the carsound cat I'm using has 2.5 inlet/outlet.

I just passed smog EASY with it, so I guess its doing its job. I can't comment on how long it will last, but I've no reason to believe it won't last for a while longer. I think it ran something like 55 bucks on eBay too, so its not very pricey.

[wrichards2005]

1) Who ever said that a DC Header loses compared to an A4 manifold?

Mine was worth a little increase in the top end. Everyone is so quick to bag on stuff they don't know. Keep in mind people, that if you were to just bolt a Bisimoto header on and got 8WHP, it isn't going to feel like a HUGE gigantic increase.

The DC routinely dynos 3-5WHP higher than the stock. Is it a great header with maximum R & D, no, but is it better than stock, in most cases.

A simple look at the collector is a good basis for comparison. I just measured these out. The other day. The stock collector has a .25-.5" smaller internal diameter. That will be good for at least some flow, even if the rest is equal to the stocker. The collectors are also a little smoother than stock, so I would expect some minor flow gains there too.

When coupled with a stock size high flow cat, the increase was noticable.

Losiracer, personally, if it were me, I would get rid of that test pipe and put your stock cat back on for now. Those are a huge source of raspiness.

Then I would consider a high flow cat. Magnaflow is cheap, but they too add a little raspiness compared to the stock cat. Apparently Catco sounds pretty good, but they are a little more spendy, so you will have to decide.

I haven't looked at the G'reddy EVO 2, but I can't imagine a quality exhaust system with no resonator...so I would check to make sure it doesn't have one already.

You're right Scott, you will gain on a cb7 with a DC Header. But I hear the gain on my current DD (97 Lude) was actually a loss, with headers such as OBX and DC.

The horsepower gain is probably around 3-5 with a manifold, but I seriously doubt its more then a 1-2 gain with a stock A4 header. I'm by no means an F series expert, but thats just my guess.

[NorcoAccord]

Get a high flow cat and you will lose maybe 1 or 2 horsepower compared to no cat. If it was me i would put another resonator about 3 to 6 inches after the 1st one.

[Losiracer2]

okay dont make fun of me lol, i managed to take a video of what my car sounds like at different RPM's and at full and partial throttle.

http://s145.photobucket.com/albums/r...haustflyby.flv