Bigger Piping Between The Header And Cat?

[AleroSS]

Hey guys, regardless of whether I end up with a 2.5" or 2.25" cat, my piping will be 2.25" on my car (after the cat) and I was just wondering if anyone would recommend, or had any feeback on doin 2.5 from the header collector all the way to the cat?

Also, is there any way (at stock height) so run the exhaust STRAIGHT down the center if I were to add to the heat sheilding underneath the gas tank (as our factory layout has the piping under the gas tank too).?

[kwhauck]

actually i believe it has been said that our cars perform better with catback exhaust and opening up from the collector to the car would hurt it.....i think it was oldsman that said this....not sure though...and unless you want to go under the axle the piping could not go straight cown the center of the car....