Re: I want to upgrade my 08 focus!!!
Keep in mind it's best to check with your insurance FIRST. If you get into a crash, regardless of who's at fault, insurance might nullify your policy if they're not aware of any modifications. Especially if you go to your insurer and they see "race" on any of the work invoices, you'll knowingly have to start shopping around. Get quotes from everyone except your current insurance provider, and then approach your current insurer to see what they have to say as you might be able to negotiate a rate, if they'll accept the alterations.
Second, there are plenty of engine options out there. Keep in mind as auto manufacturers are going Global, engines aren't necessarily vehicle specific anymore. Squeezing in a 2.4-2.5L I4 is one thing, but mounting a V6 transversely, getting the transmission mounted, and axles to line up level without giving you gobs of torque steer, is another.
Lastly, to be frank, if you cannot handle a job such as this yourself (75% of the work load), you'll be looking into the five figure mark to get a conversion done to a V6, much less for a larger 4 cylinder depending on the vehicle it came out of as it will simplify things to get the engine mounts to mount up. There is a 2.5L V6, but the HP it offers there are better same displacement I4's out there. Going with a 3.0L 24V will be a tight fit. Suspension changes, and changes to the body will have to be made to accommodate it. Manual transmissions are generally more compact, so if you have an automatic now, it's something that might not be available going with a V6.
The 3.0L 2V V6 and 4 speed automatic in my old '99 Taurus is wide and takes up the width of the engine compartment. In your case, you will knowingly have to relocate the battery to an alternate location (trunk), among other things.
I will commend you for doing a project like this, as it will be rather unique! Finding a custom auto shop that will take it on shouldn't be much of an issue. The issue, will be the overall cost as it will be double if not quadruple what the vehicle is currently worth.
'00 Durango R/T 360ci 290hp (modded); 138,500m
'06 Pontiac G6 GT 3.5L 220hp; 44,000m
'12 Chrysler 200 Limited 3.6L 283hp; 13,000m
'99 Taurus 3.0L 2V Vulcan 145hp; 154,300m - Traded
Amsoil in all vehicles!