The stock pipes are surprisingly good. There is a link to a spaghetti Vs oem system and the bang for bung ain't worth it. The spaghetti system gains a couple of hp at the very peak but that's it. Throttle response may improve but I don't have FHE on that. I'll look for a link from Doug Lofgren. Maybe a racy system might help with other big mods. Stain tune once made a system with that type of enhanced crossover and larger diameter pipes. Maybe 45mm iirc. I lost the catalogue.
Oh, I forgot to mention, spaghetti pipes are as expensive as hell, and mostly good on the top end. Not really appealing to me, although they look cool.