Where is thermostat located in the Suzuki Forenza 2006

Either at the engine block located at the end of upper radiator hose. However it could be located in the lower radiator hose like mine was.

Loosen the upper radiator hose. This is the hose that connects to top of the radiator to the engine. Loosen the hose on the end that connects to the engine by using a flat-tip screwdriver to loosen the circular clamp.

Remove the hose. Pull the upper radiator hose off the end that connects to the engine. Have a drain pan underneath the hose to catch any coolant that remains in the hose.

Loosen the thermostat housing. Use your ratchet and socket set to loosen the bolts that hold your Mitsubishi's thermostat housing in place. The number of bolts and their locations vary based on your Mitsubishi model

The thermostat will be located either at the upper radiator hose inlet to the engine, or it will be located at the lower radiator hose inlet to the engine.

Remember that the spring end of the thermostat should always go towards the engine, and not towards the hose.

Also with a lower mounted thermostat, when it comes time to add coolant you should dis-connect the upper radiator hose at the radiator and fill the engine through the radiator hose, if you do not then there will be very little coolant in the engine block until the thermostat opens up, and by then your engine could be toast.

To locate the thermostat follow the upper radiator hose to the point where it enters the engine. The thermostat is located below the coolant inlet that the hose is connected to.

To change it:

You're going to lose some coolant, so have a bucket or other container, and some fresh coolant ready. Follow the upper radiator hose to the point where it's connected to the engine. The hose is clamped to a metal housing (water inlet) which is bolted to the engine. Remove the bolts (not the hose) and lift the housing to expose the thermostat (may require a little prying with a screwdriver or similar tool). Note how the old thermostat is fitted (which end is up), lift it out of the engine, and then remove all traces of gasket from the housing and the engine. Install the new thermostat and gasket, replace the bolts, add coolant as necessary, and you're done.

Before you start the job though, check the condition of your upper and lower radiator hoses. If they show any signs of wear, fraying, or fatigue, you might as well replace them too.

BillB

The thermostat is located on the engine block, where the upper radiator hose connects to the engine. You'll see a large elbow-like component that is attached to the engine with 2 bolts.
Just follow that upper radiator hose and you got the location. When you remove that housing (elbow-like component), you'll see the thermostat.
Make sure you note which end of the thermostat is up and which end is down. Don't reverse the install.