I know what I told you in the pm which is basically what has been said here. Then the coffee started to kick in. I'm running a Plog and 3" dp into a high flow cat and GTP exhaust on my Regal with an L26 under the hood. On 2.93 gear ratio, it's oddly fast. But then..NA's aren't really that slow after you've been ... ok they are ..
There's merit in the back pressure mention. Yet there's flow at the top end too. Headers won't hurt your NA, expecially if you have future plans. Although, it's super easy to slide a set of headers in when the heads are off and even easier to do the lim's on an NA in under 2 hours.
