The 3TC 1.8L engine is pretty well setup as it is. Look at the intake and exhaust manifolds. Intake on the right and the exhaust on the left. That is a race car engine inspired crossflow head. The intake has long intake runners, very nice, make lots of power.
The exhaust is 4-2-1 as in 4 into 2 into 1 exhaust. Very nice. makes power.
Also the engine is what is known in racing circles as a HEMI !! very nice makes lots of power. Infact the hemi head is almost a direct copy of the famous Hemis from Chrylser.
One thing you might want to do is put in a bypass for the cat. vn mlop. If emmisions laws in your area allow it.
Also if you still have the original spark plug wires, get a set of Magnecor KV85s.
Give it a good tuneup and it will make lots of power. Very nice, with good gas mileage to boot.
If you can find a EFI setup from a 3TEU that will get you a good power boost.
Very rare but very nice.
www.magnecor.com
Hemi3TC