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Discussion Starter · #1 ·
I am going to purchase the Arrow/Triumph 3into1 soon. Does the new header have the same precat and o2 sensor? Looking at pics it seems that the Arrow exhaust is devoid of all the emission crap. I wonder if your modified header flows as well or better than the Arrow header. Lastly is there a weight difference in the headers if the stock header is modified to your recommendations?

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First, I have NEVER seen a dyno graph for the Arrow full system and anything I say about it would be conjecture or based on an educated guess.

Copied from the Custom Header thread:
I saw and measured the Arrow full system (with header) at a local dealer today. A couple of interesting notes. It costs USD $1300.00 through the dealer (at least THIS one). It comes with a new oxygen sensor, and DOES have a precatalyst in the collector - although not nearly as restrictive as the stock header.

The primaries are slightly shorter, and the collector is a flat design like the stock part, but a bit better made. The flanges and collector are held on with springs. It is considerably lighter than stock. The welds are good, but the welds on the collector could be better.

The tubing is 0.049 inches thick.

The primaries have an id of 1.395 (35.4mm) - slightly larger than stock inside.

The collector id is 2.00 (50.8mm)inches (not including the precat). This is a good bit larger inside than stock. The precat is about 1/8 inch (~3.175mm) thick.

Notice that the primaries are slightly smaller than the Zard, and the collector is a good bit larger - but it has a precat/baffle/absorption material in the collector that necks this down a bit. As precats go, it is a nice design, and much better than stock.

Side note: The Zard header has a precat as well.

Arrow still doesn't list the full system on their site, only the half systems.

based on the measurements of the Zard and Arrow full systems, I would expect very similar results from the Arrow full system as Avi8or had with the Zard full system. And I know little about the tune that is available from Triumph for this system. I do not intend to knock this exhaust system, but until I see dyno results before and after that prove otherwise, I would expect little to no gain under 6000 rpm, and perhaps a small gain at higher rpm - if the header and silencer can flow enough to make more power.

The slight weight reduction by removing the baffle/precat in the stock header is not worth talking about. The Arrow system is considerably lighter.

TightTL has done some work on his stock header and shown the gains this work provided using the TORS tune. I believe today he will be on the dyno again and be using Tuneboy to tune the bike for even better power and torque. I would suggest waiting for these results to make up your mind. ;)

Discussion Starter · #3 ·
Thank you for the fast reply and thorough explanation, I think if I go with the Arrow exhaust now it will be for weight reduction and looks.
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