It depends. If you have some to a lot of mods like, header, performance exhaust, pulleys, CAI
, etc then yes you might as well tune it to get more HP. Now for turbo it depends too (remember you will still need a tune), if you planning to make it turbo and aim for 300 to 350 HP then yes it will be great because at least you can still use it for daily drive. Now if you are aiming for more than 400+ HP on a GT then you should have another car for daily drive (commute) just in case because I wouldnt recommend it to be used daily. Basically if you cant afford it then NO. But thats my opinion, at the end of the day is your car you do what you pleased.