Removing the Catalytic converter

[Rasher]

Not forgetting the biggest issue with the low down power is that 1st - 3rd gear is restricted, the headers obviously allow the engine to breathe up top and give that huge peak gain, but the flash gives increases in the 2k -5k range in 1st - 3rd, my dyno tests with just CJM (which we now know is far from optimal) gave around 25% more power at 3,000rpm, and we know 1st and 2nd are even more restrictive.

If you only had a few hundred bucks to spend a Flash on stock exhaust would be my recommendation, but there is no doubt the cats cost the bike a lot of power past 5k, from my experience of the bike with just the headers (and no fuelling changes) I would say the poor running at low revs is too much of a trade-off for a bit more top end.

Not sure how a stock pipe sans-cat compares to the Arrows as the shape will not be so good, but if you can do it yourself for free then it has to be good value ::008::

 

[p51super10bombay]

Would a gen2 flash alone be sufficient with a gutted stock header and an Akrapovic slip on?

 

[Rasher]

Would a gen2 flash alone be sufficient with a gutted stock header and an Akrapovic slip on?

Almost, mine has the slightest surging around 1700rpm on very low throttle openings, easy enough to ride around - I have yet to try using the O2 eliminators I bought off E-bay to see if that cures this completely, but it is not too bad - hence I have lived with it for about 6,000 miles ::008::

 

[frez]

So what's the best solution? Arrow headers plus Hilltop ECU reflash? Do I need O2 Eliminators for best solution and if so do I need a PCV too or just the ECU reflash?

 

[Big Blu]

What apart from all the folks that have fitted Arrow headers and provided before and after power curves (like myself)

I gained about 6BHP from the headers alone, with the Flash it was around 10BHP more, the headers gave noticeably better breathing up top, the Flash totally transformed the part throttle response and mid-range.

The only issue is fuelling with headers alone is poor, and possibly dangerously so, but if you have the extra cash to sort the fuelling and would like more power then it is well worth the effort...



Just monsters the stock engine throughout the range, and feels like a bigger gain than the graph suggests, just soooo much grunt from 2k - 5k

Do you have a curve that shows PC tune with out the header? That would be the only accurate comparison....

Paul

 

[Rasher]

Do you have a curve that shows PC tune with out the header? That would be the only accurate comparison....

The problem is the curves do not show the real gains on part throttle and removal of 1st - 3rd gear restrictions, the benefits of the Flash have been endlessly discussed and there are several "results only" threads to work through if you want to find out more on the effects on a stock exhaust.

I think the question here is how does a strip of the cats compare to an Arrow, I know the arrow headers alone give 6BHP, but how would de-catted OE headers compare :question: My guess is they may not be quite as good, but removing the blockage should add a similar amount (maybe 4-5)

The problem is the fuelling will be off, so a flash / power commander would still be needed and a PC alone will not solve the low gear restrictions.

 

[outdoor]

What apart from all the folks that have fitted Arrow headers and provided before and after power curves (like myself)

I gained about 6BHP from the headers alone, with the Flash it was around 10BHP more, the headers gave noticeably better breathing up top, the Flash totally transformed the part throttle response and mid-range.

The only issue is fuelling with headers alone is poor, and possibly dangerously so, but if you have the extra cash to sort the fuelling and would like more power then it is well worth the effort...



Just monsters the stock engine throughout the range, and feels like a bigger gain than the graph suggests, just soooo much grunt from 2k - 5k

am i reading this graph wrong, but is it not showing the HP peaks above 100HP? How are some people getting 110hp?

 

[fac191]

I think you would only get that if you raised the rev limiter. If you get 100hp at the wheel your doing ok.