'09 FLHX stock, SERT tuned, SE/AC, supertrapp slipons. Want some more power. Was thinking of few options as I want to use all HD parts. Today I priced some OEM heads for 12-13 models that have the ACR's built in $800 for set. I want to either install heads and 255 cams and leave as '96, or also include 103 cylinders. Would heads work with either '96 or '103? Or more cost effective to have oem heads machined for ACR's? My main concern is the compression if I install cams and bigger cylinders thanks.

 

Do not pay $800 for a set of heads. I have a set in my garage that are from a stock 103 with ACRs that I would gladly take $450 for. I bought a set of new castings that we're drilled for ACRs for $300 that I sent off to be worked over. There are plenty of take off head sets to be had for a decent price.

Your heads are almost exactly the same with the only real difference being the ACRs. If you have a 96" and wanted the 255 cams, personally I'd just change the cams and leave everything else alone. My opinion is that the 7cu increase to a 103 is not enough to warrant a ton of money and the 96" does not really need the compression releases if you religiously start the bike in neutral.

That said, if you are going to change the heads and cylinders and cams, at least go to a 107, add a GOOD cam for that displacement and compression, and have the heads worked over by a professional.

Just my humble opinion.

 

Going from 96 to 103 isn't worth the money. If your going to change the bore go either 106 with S&S or a fuel Moto 107.
I went 106. I've got 107hp/115tq to the rear wheel. Mine was a 96.

 

I have a 103 on my 09. Its just bigger cylinders and pistons with stock heads. Don't think there is a difference in heads between 96 and 103.

 

Depends on compression, and cams....

I think the 96" motor was 9.2:1 compression, the factory 103 ( power pack) in 2011 was 9.6:1 the ACR's are nice especially with the SE255 cam I had installed.

For future engine mods, compression releases not a bad way to go. I did not get them and wished that I had on my 103 build I had done on my 07 fatboy which had 9.8:1 compression, heads by Baisley with their roller rockers, and a redshift 575 cams. it had hot start issues that compression releases would have resolved.