Palsut, don't do the 3.8 engine until you have problems with your 3.1 engine. It doesn't seem like your fully into the swap so I say stick to the 3.1.
I want to do what rook has done but I'm not going to do that until like a year and a half from now because I'm almost at 200,000 miles and the tranny is slipping a little bit.
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Exterior- stock painted black wheels, clear corners, stainless steel grill, cross and drilled front and rear rotors with evolution brake pads.
Coming soon- 18 inch black mustang bullet rims, GT/GTP rear bumper, tinted windows.