What do the fuel lines hook up to on the carbs for 95 katana 600f

IT IS THE LARGE LINE GOING INTO THE CARBERATOR

This motor has Carburators unless modified the carbs sit under the fuel tank one for each cylindert.

If by "tune up" you mean synchronize, you'll need a carburetor synchronizing tool first. They are either fluid based, mechanical manometer ones or electronic. Search for "carburetor synchronizer". You'll need to take the tank off and hook up a temporary fuel supply (rig it up or buy an external tank). For oil cooled engines like your GSXR/Katana/Bandit that have no fan you will also need a strong external fan to cool it.

This engine has four carburetors and they are synchronized in pairs. Small Philips head screws are located between the carbs. Hook up the sync tool to the vacuum nipples on the carbs. Hook up the external tank. Warm up the engine. Using the idle adjustment knob, raise the engine speed to recommended rpm. Using a screwdriver, adjust so that cylinders 1 and 2 are on the same level (the exact level does not matter). Do the same for 3+4. At last, use the middle screw to eliminate the difference between left (1-2) and right (3-4) pairs.

That's pretty much it. A cursory search on Katana specific forums or Google will yield plenty of more detailed instructions and videos. This is an easy job. The hardest part is hooking everything up, but even that is hard to do wrong.

Here's the link to the manual:
http://www.metal-fab.net/files/1988-1997-GSX600-750-1100F-R.pdf

Just so you know, it loads slowly.

indicates a fuel problem
wide open throttle and back firing indicates low float level or fuel flow problems
check for tank vent is working as it could be a vacuum forming in the tank preventing full fuel flow

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First things need to do : check your carburetor and ignition system
Make sure they working well.

Suzuki Katana 95 ( specs.
Carburetor 1988-1997: Mikuni BST32 x 4
Ignition type: Transistorized
Ignition timing: 13° B.T.D.C. below 1500 rpm

check carb float level and firing order, out of time

http://katriders.com/vb/showthread.php?t=56167

floats are stuck allowing fuel to flow . remove carbs and rebuild them slowly you ll need to set float levels too