Personally, to do anything to a Tib and make it more than a eh car is going to cost som $$ and be completely custom. As far as making large HP and keeping it streetable, it is do-able, but at a LARGE price as the above statement… completely custom and a good amount of $$.
Your best bet is do the simple intake/exhaust bolt-ons. If someone offers a cam swap look into it.
If you want to go more; I don’t know too much about those motors, but a small turbo setep would be the next step; this would be a custom setup (Talk with Focusinprogress; he did a great job with his custom Focus project), but that’s still going to cost some $$. If the tib motors are glass, then any sort of bosst is going to require ripping into the block for a rebuild; thus more$$.
A car like that to make into a respectable street car is going to take a lot of effort and cash; something that some people are willing and able to do. Personally, if you want a DD car, do the basic intake/exhaust mods and leave it at that. If you want a “toy” or Fast/reliable DD, look into another car.