The amount of 98 kits out there are well in to the thousands, and by design they offer more relability than a cast bore/ liner cylinder. There are several on the board here that have the 98 kits. The added bottom end tq is much more than a 95. Cooler oil temps of approx 20-30 most time I see 20 here in AZ. A few have told me they have seen more in other regions of the country. The 95 is less money but when you see the dyno comparsions you see the 98 really shine in the tq curve from 2000 to peak tq. The extra 3 inches really makes a huge difference. Not taking away anything from the 95 great kit low cost, makes good gains.
The 98 inch kits have a life time warranty, I am not aware of any 95 that offers that. Price wise not that much more really. Most builds are very mild and offer gains that to be had with a 95 are going to require much more money. Adding large cams, roller rockers, pushrods, and the peak number may be close but looking at the riding area the 98 is building faster and harder.
98 with a 37G cam and my stage I heads is making 97tq at 2500
95 with 37G cam and Stage II head will peak at the 95-100
Seeing the graphs side by side is where you really see the pumped up tq curve. I will go through my sheets and see about posting a few. I have one that has deweys heads on a 95 with 37 g cams bike makes great numbers both at the 100/100 mark. Please do not take this the wrong way, hard to make a 95 run with a 98 this is not a statement to say any thing against any ones head porting ablility. But peak numbers are a small part of the deal, when you can add 25+ lbs of tq that is great, now add that to a custom set of heads such as Deweys and man on man would you have a stump puller!!!!
Customer bike here has the 98 with a S&S 585 making 113 tq and 106 or so hp?? I am unsure of the Hp maybe he will post the numbers?????