Few questions about IQR mountain

I need few info's about the IQR.
There are a lot of people building IQR here and a lot of good looking sleds but nearly all are following different ways.

if i look to that sled here
http://i419.photobucket.com/albums/pp279/SUPRATURBO0501/Resize20of20P10106341.jpg

i like the design and it looks really awesome.

What is the best tunnel extension? (i like that one on the pic)
how about engine? 600rr is a HO how about a turbo 600 version?
which is the best track length? 144? 146? 149? 151?
i personally love the RMK track but camo extreme should be also a good choice.


the rest should be a easy choice ezryde, holz and all the other good brand's we can use for parts.

i think i will find a 600rr somewhere in US or sweden for the IQR project.

thanks

thanks for the info. that sled is **** for my eyes
only thing is that long track. i like more shorter one 144 or 146.


i think iqr should work with camo Ripsaw 1.75in 146"
that should be a nice length for spring days and for fun.

for deep days and hill climbing i stay with my BD RMK

600 big bore should be a good point. then i already have a turbo in my RMK so 600 should move 146 track very quick. and carl's 685 is a real killer.
Fitting 700cc engine with turbo is to much work and i already have a turbo sled

i like the z-bros a-arms

so what rear skid to use?
tunnel or extension?

for now

1.75in 146" or polaris rmk 144" track are looking best to me.

ez-ryde rear skid or rmk 144" rear skid

685 carls bb
z-bros a-arms
fox shocks

and few nice parts from RSi and SLP

are there any rail extensions for 600rr to 146? i can find only 144.

i will go with 146 ripsaw 1.75
i will use 144 extension which should work fine with 146 track (wheelie)

i go with 685 big bore and wiseco racing pistons.