Fairly sure they are different. The 116 manifolds are in 2 pieces with cylinders 1 and 4 coming together to a downpipe behind the engine mount, and cylinders 2 and 3 coming together to a downpipe in front of the engine mount.
As far as I can remember, the 105 series manifold downpipes both sweep behind the engine mount.
I agree, do the port matching, or make the exhaust manifold ports slightly larger, it slightly increases bottom end torque where wild cams are used. (Anti-reversion technique.) Remember do do your gaskets as well.
And unless an aftermarket manifold is really (i.e. precise) well made, do not waste your money.
I agree with everything said, personally I prefer the 116 branches to the 105. The 116 lengths give larger volume and lengths are more equal. They are still not long enough for max top end power but gives the engine mid-range torque.
The concept Jacques is talking about, means the diameter of the runner in the branch is 2-3 mm larger than the port. This will give you a 1 - 1.5 mm shoulder around the cyl. head's port.
I'll go first..... sorry, I have not got any decent pics of the 159 handy.....
Frost the 155 is just for you. I honestly wish I still had this.
I did not post the 147, 156 , and various Suds\Sprints up here but somewhere on this forum there will be a few pics around.
I have a 2006 GT 3.2 V6. It suddenly started to make a rattle noise after the car is warmed up and if the revs go over 2500rpm. There is is no noise when the car is cold. And nose is gone if revs are under 2500rpm. The rattle is more than a clicking sound.
Any help advice will be appreciated...