res delete = instant raspy, cat delete = normally ungodly loud and annoying. If you must you can get a high flow magniflow uni cat from summit for about 100, leave the res cause that calms the rasp down, then decide on a muffler. I personally like magnaflow but i've only used them on v8's, never piped a v6 especially a boosted one at that, so that being said, which was said before every car is different but no res never sounds good. IMO