Presently struggling to persuade myself to part with a fairly large wad of cash for a replacement exhaust. But would much like the freely breathing engine that JMo and others have described resulting from fitting a decent exhaust, and DNA filter/airbox and either the Kev mod or a PCV.

How restrictive is the OE exhaust? Is there any point in doing the less expensive inlet-side mods, but leaving the standard exhaust as it is for now? Would this deliver any noticeable benefit?

Or is there some glaringly obvious reason - maybe involving the cat - that I have missed, that makes this unwise or impossible?

OEM exhaust is NOT too restrictive. and if you keep the lambda sensor the cat should be fine.

have fun,

j.

Giving the bike more air & fuel offers more gains then adding a exhaust by it's self. Fitting the DNA filters with a fuel mod will show good results on a standard exhaust system.

If you have the cash I always recommend fitting a PCV as this is the best fuelling device by far, for a less cashed up fuel mod there are a few to chose from these days.

I know this thread is about the X&R but it has the same motor as the Z & the gains are very simular.
http://xt660.com/showthread.php?t=4509

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Mods that I have done to my XTX's

My 04 XTX
Stage 1 & 2 DNA filters / Kev fuel mod / snorkel mod / Drilled air box mod / Engine breather mod / Fork Spacer mod / 15w fork oil /
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My 07 XTX
Raptor 700 cylinder 102mm / Modified Crank Case to take a 105mm Raptor Cylinder / 11:1 102mm JE Raptor piston / Stage 1 Raptor Hot Cam / Ported head / Colder Spark Plug / +2mm Throttle body / DNA stage 1 & 2 filters / Modified Air Box / Snorkel removed / Worry Brothers stage 2 filter cover / 6mm & 8mm Bolts Replaced with Titanium Bolts / Recovered seat in Black / O2 Eliminator /

My 09 XTX
59HP at the rear wheel / Stage 2 Raptor Hot Cam / DNA stage 3 Air Box / Carbon Can Exhausts / Modified Exhaust Link Pipes / PCIII With Custom Fuel Map / Wideband Commander O2 Data logger / LCD100 Dyno Jet display & fuel adjuster / 2500 OHM HT lead instead of a 10K OHM XT lead / Extra Coolant Cooler / Protaper Fat Bars / Tail Tidy With LED Tail Light / OKE Protection Knobs / LED indicators / AIS blocked / Modified rear sprocket rubbers / Rear Foot Pegs removed / 09 ECU With 02 Sensor Changed To A 06 ECU / Complete wiring harnes Changed from 09 to 04 / Home made LED resistor flasher / Hole drilled in the fuel tank filler neck to allow quicker filling / Modified Bar End Weights / Progressive front fork springs, 15W fork oil, forks lowered 25mm, used XTR rear links lowering the rear 20mm, rear spring one click stiffer / Changed front & rear guards from blue to black / 47T rear sprocket / Speedo Healer V4.0 / Kev throttle cam mod / Throttle grip mod / The new 2010 O2 sensor mod is out, works a treat, The new 2012 O2 Controller is out, PM me for details

Now ride a 2018 MT09SP ABS + TCS

My KTM 990 SMR Mod book. http://www.ktmsmt.com/viewtopic.php?f=13&t=4946

Thanks Guys. Kev - looks to be some worthwhile gains to be had. I'll be giving this a try in the New Year, I think.

Alan, the offer still stands if you want to have a go on mine you can then do a back to back test with yours so you will get an instant result for you.

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:tenere:

Mods, Oxford heated grips, Givi Rack and top box, Stage 2 DNA filter and top, 02 sensor eliminator, Metal Mule taller screen, Seat hump trimmed off, .KEVS FUEL MOD (THE 1ST ONE FOR THE TENERE) , Extra fuse box, 12volt plug in socket, Zumo550 sat nav, , Barkbusters


What Bill Clinton REALLY said to Monica Lewinsky was: "Sack my cook"

Sadly Bike now sold 11/6/11

But I've just noticed the LeoVince cans are now down to �359 on ebay!!!

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Never underestimate the power of stupid people in large groups.

Thanks Rick: I'll take you up on that, please. I'll give you a shout (via PM to save boring everyone else!) over the Christmas break, and maybe we can meet for a ride, a coffee and a natter.

Unless any other Somerset-ish members fancy a bit of a meet up/ride-out?