Hi
Assuming that OEM exhaust without cat will help for lower engine temperature, I am asking for advice. Please take a look at the following picture:
http://picasaweb.google.com/petrest8...99123041611506
-Is it easier/better/possible to remove the cat through the window (along red line), or just to cut the pipe along yelow line and drill big hole?
-Is it worth/useful for achiving lower engine temperature?

Thanks for your time.

The cat is very hard to get out. I would cut the pipe on the left side line, before the dotted line on the weld.

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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 /
[
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

As Kev said, It will be better to cut through the welded joint of the tube to get to the cat, will be better for two reasons:

1.- Better clearance to get the cat out.
2.- You can weld again the tube and nothing is noticed.

I remeber seeing some pics in the forum of a dismounted stock exhaust, can't find them now. If I can get some second hand oem cans I will try to do that, remove the cat and doing some things more. But only on cans I can break or loose, oem mines have to be ok for technical inspection.

Thank you Kev.
My plan was based on this
http://picasaweb.google.com/petrest8...49707346115586
Can you confirm, that this chart is correct? I have found it on German's web site.

My intention too. But I am scared that cutting on welding line will desintegrate some internal parts of the silencer. Or am I wrong?

Well, as long as you do it with care nothing has to be wrong. Just use an small radial disk cutter and only cut along and not much inside the weld.

OK. Than...what about chart and benefits regarding the heat...if any.

The charts is correct.

If you want all the photos' & on how to do it step by step, it can be found in the modification index.

http://www.xt660.com/site/node/325

Exhaust

Page 2: Standard Can Modification.

There are 15 pages of photos & intructions on how to do it.

__________________
Click here to join the XT Supporter's scheme

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 /
[
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

Thank you for confirmation.
Regarding the heat and cat, I have found results before / after and they are about 30 C lower on the headers, but including aftermarket silencer. If I get half of that result, I will be happy enough to mount back my bash plate for offroad riding. Just for peace of mind. Thanks again guys.

Mission accomplished. The most important things is to have really, really good welder with sense for art.