Just wondering if anyone has ever considered only replacing the front exhaust header with a more efficient tubular design without changing the backside one :?:

It would obviously be a lot cheaper and easier than doing the back one too.
There would be visual benefits also.

Would it create an engine imbalance? I doubt it. The front side is already more restrictive by the fact the exhaust has to turn 180 degrees to get around to the back which exits straight out.
The rear exhaust header is tubular from the factory. Ya I know replacing it too will yield more efficiency but hey it'* a lot more effort and cost than just the front one.

Presently you can only buy a complete set so the option isn't even available.
The only way now to improve the front cast header is to manually port it.

If there were enough interest maybe one of our vendors could look into it.

Actually I did look into it. Replacing the front exhaust manifold basically allows the engine to breathe much much better. It feels much more balanced in the power delivery, just smooth all the way throughout the rpm band. Making a tubular front exhaust manifold is possible, but in the end its cheaper to modify the stock ones since there are plenty of cores out there. It is cheaper and the power gains are pretty close as just replacing the front one.

We are going to be offering Ported Exhaust Manifolds for Series II engines once I process the pictures, it will be on the ADTR site shortly. I also ported the rear exhaust manifold and even tapered it down, it helped quite a bit. Pricing should be in the $200 range.

By porting the exhaust manifolds, do you mean taking a Dremel to them and hogging them out a little?? What kind of power gains can you get from doing that??

I bet the claim will be 5 - 10 hp.
I'm not sure I would like to attempt it myself. I'm not even sure I would buy a dremelled out cast iron header unless there was a warrantee against cracking.
They're thin wall castings....just a guess...but even if they have some meat to them, cast iron is prone to cracking.
I would also guess that the material is just taken off enough to match ports of the heads and gasket in order to minimize turbulence. Not sure how far you could reach with a dremel tool inside the small passages.

I would be interested in purchasing a performance tubular header that mates to the existing crossover pipe connection. One with larger (not too big), smoother, matched pipes to begin with.
At hopefully half the cost of a complete header system.

I have had the test ported exhaust manifolds on for many months, there hasn off enough to match ports of the heads and gasket in order to minimize turbulence. Not sure how far you could reach with a dremel tool inside the small passages.


I have had the test ported exhaust manifolds on for many months, there hasen't been one crack, I check every week. The power gains from this is well worth the money. This is one of the best modifications you can do to your car other than Ported and Polished heads. You cant use a dremel... it takes too long. Use a die grinder.

2000SilverBullet, not to put you down, but you make alot of assumptions without backup. I am actually doing these products on my car and bench racing them. This is from real world testing and experience. It really is not worth it just ot make one side ofen't been one crack, I check every week. The power gains from this is well worth the money. This is one of the best modifications you can do to your car other than Ported and Polished heads. You cant use a dremel... it takes too long. Use a die grinder.

2000SilverBullet, not to put you down, but you make alot of assumptions without backup. I am actually doing these products on my car and bench racing them. This is from real world testing and experience. It really is not worth it just ot make one side of the header. The performance gains are going to be the same as porting because you are still connecting the rear exhaust manifold then it goes to the downpipe. All the aftermarket headers seperate the front and rear exhaust front each other flows and connects in the downpipe. Just like TOG, *&*, etc. What you might be interested in more is a tuned downpipe. :P

True, I do make assumptions and I'm sorry if I offended your pride.

I agree that real world testing beats theory most of the time.

I read the ZZP article on their ported manifolds and am impressed at what they have to offer......and they're ceramic coated....and half the cost of ceramic coated TOG tubular headers.
Looks like the new Series III motor uses a ceramic coating on the cast iron headers also.

Did you dyno the real world performance gain :?:

I am probably going to price our manifolds around $100-150. Just have to make sure cores are available and to get some. The ZZP'* ones ar ghetto ceramic coat. I think it'* ceramic paint. I don't think they they actually coat them. Haven't dynoed them yet. Dyno time is expensive and would have to offset the cost first. If there is high demand I will dyno.

I had my crossover Jet Hot Coated just cause.... I could set up a deal of having about 3 or more done and it would cost like $50 dollars each. Would you prefer Jet Hot iRocco :?: , just for you.

Hot dang, sure I wouldnt mind having those. Hey you didn't get back at me about that hi-flow muffler and cat. Sure would like thoes too. TY.

You want 2.5"? Or 3". And what kind of muffler do you want as well and size.

, this is what you told me. But you never got back at me.