they will be about the same since they both have the same porting on them, between 12"-16" you wont see a performance or noise difference
They are both around the same performance. The J&J may be slightly better, being ceramic.
The threads are Tippmann Barrel Threads
The 68 does not have a removable barrel.
The first thing is usually a new, longer barrel.
Yes, the tippmann 98 and the tippmann custom are the same marker, therefore the threading of the barrel will be the same.
This statement is half true but half untrue. The tippmann A5 and 98 custom do indeed have different threads. But after the A5 tippmann made the X7 which has identical threads to that of an A5. Because of this a barrel with "Tippmann A5" threads, will fit on a tippmann x7, but will not fit on a tippmann 98 custom.
Sadly no. On the end of the barrel are the threads, and as one could see the threads on the end of a Tippmann barrel are thick. Spyder threads are much thinner.
the barrel, hopper, stock, and many others.
No it will not. the Handguard on the barrel is in the way of the handguard on the shroud.