i want to get a couple of mods, but i dont know what combination to get them in, can you guys help? The mods i want to get are downpipe, racing radiator, AST, and cat-back exhaust. someone told me that i will have to get a computer to comply with these mods because the engine wont operate effiently without a computer to even out the engine. is this true? also what else would i need to comply with these parts? thanks!