Exhaust question

[stogieluvr60]

I already have the "low end" stage 1 Rushmore bike that you speak of and its decent but just not that much fun anymore. It just does't have the torque that I'd like to feel in the seat of my pants. I'm just wondering if I'd be happy with a set of cams and a good tune or spend/save a bit more and do that along with the 107". I really don't want to get a new exhaust though because I like the sound of my Slimlines and I'm sure they'd be fine.

skip the 107 and do the 110'' drop on kit...have the heads freshened with at least a true performance valve job (if porting isn't in the budget) and slide in some CyvleRama 575s

hi flow air cleaner helps at higher rpms if desired

kickass tune and Bob's your uncle 

I never quite understood the whole 103" to 107"....juice isn't worth the squeeze...but with these drop in 110" kits on the market now...that's another matter.

[Ketch]

The difference is money. Gotta do head work if you move up to 110"

[Hossamania]

The difference is money. Gotta do head work if you move up to 110"

If you're not doing head work, what's the point of going from 103 to 107?

[Ketch]

107" equals torque. Head work equals horsepower. It's kinda like being on a budget and you only have so much money to work with. Would you keep it a 103" and do cams and head work or go cams and 107" with no head work for close to the same money? Answer is 107" if you're like me and want the torque. I'm not in need of the big HP I want the seat of your pants pull from 2,500 to 4,500.

[PoorUB]

If you have the heads off, get them done. Even more so if you are bumping the cubes. It is not that much money compared to the rst of the build.
Porting will also help out in the lower RPM range.

[harpwrench]

The difference is money. Gotta do head work if you move up to 110"

Check out GMR's posts in the dyno section of 110 drop ons with stock heads

[motolocopat]

The difference is money. Gotta do head work if you move up to 110"

Check out GMR's posts in the dyno section of 110 drop ons with stock heads

Yes Steve/GMR has stated several times and others as well that the 110" kits just seem to work well even without doing Headwork. I suspect that they are pulling sufficiently more volume that they create higher velocities that there is just a sweet spot that they are hitting. From what I've seen the 107" kits need cam/headwork to produce the same amount of power that the Bore/Cam 110"
Obviously while you have the heads off they should be checked and as suggested just a good valve job if your mileage is up there on the bike or is affordable.   

[rhuff]

I second everyone else questioning 103 to 107.  Yeah, it equals about 4 ft lbs of torque.  A complete waste of $$. 

Save your nickels and do it right.  Or do a nice cam (Andrews 48 or CR 570) in your 103.