Thruxton Thruxton R Headers

Because you would stop the gas flow where you cap it off I believe. The gas is diverted from the header into the cat and back into the pipe to the silencer as I understand it (don’t own a Thruxton) , hence the cat delete “X” pipe.

 

I have the Arrow header pipes which leaves the cat in place and comes supplied with circular steel caps to block off the cat. Works well, bike has run like a dream with no issues for 2000 miles and sounds amazing, in fact too loud with the baffles out of the V&H pipes.

There are other manufacturers of the down pipes, just a suggestion but slightly more expensive option than an X pipe or your idea....

Someone told me the standard downpipes have a double skin reducing air flow, never checked .....

 

Arrow headers do exactly what the first question asked, you can’t blank the cap to the cat without an “X” pipe as there is no pipe between the first bend to the cat and end cans. It’s a fake outer of half pipe .
All I’d say is Arrow downpipes with baffle free cans is mega loud

 

Not to mention arrow headers cost about £500 up to £600 depending on where you buy. X pipes are considerably cheaper.

 

Does anyone know what the power difference or losses are for X pipes and straight headers?
Also I know the Arrow headers come with o2 sensor blanks and direct software changes, do these apply to X pipes
By the way I’m not selling Arrow downpipes or saying X pipes aren’t better,I’m curious as to the differences.

 

Couldn't comment on power for Arrow headers but I have a thread in this forum about my Power Commander map and the torque increase across the entire lower rev range is substantial. Whatever you do, don't get too hung up on BHP gains. There's far more to a good tune than that.

I think using straight pipes and doing away with the balance pipe and cat necessitates more complex tuning. A PC5 on it's own allows fuel and timing to be changed. Without a balance pipe they may need to setup each cylinder independantly and an Auto Tune box is required for that. That's my understanding but I'm by no means an expert and this wasn't relevant to me.

 

That’s exactly was I was getting to,as the Arrow version as far as I’m aware doesn’t need a remap so cost wise they should bothe be very similar X pipe with power commander and straight pipes.
Only problem is without an explanation of both were scuppered

 

There's plenty of annecdotal evidence offered that says remaps aren't necessary for all sorts of mods but my AFR plot for the bike in standard trim other than de-cat and V&H silencers was pretty poor and suggests that these engines benefit from the fueling and timing being revised. I've no idea about the Arrow revision of softwre but I'd be interested to see an AFR trace for it.

This is the stock AFR trace after the '12 minute' tune:


And after PC5 mapping:

And here's the torque increase across the low end of the rev range:

 

I’m a big fan of Power commanders, and what they can do not a fan of the Autotune that messed my Daytona up until I removed it

It would be really interesting to get a set of Arrows on a dyno.