I was checking out the underside of my car where the header connects to the cat and notice that the 2-tube portion of the 4-2-1 exhaust is 2 inches in diameter. Where the 2 tubes connect into one is also 2 inches (or half the exhaust area of the previous section). This should be the weakest link (or bottle neck) of the stock header. So I was thinking what if I cut where the 2-tube connects into 1 (just before they join, where they are still separated) and combine them into a bigger collector say 2.5 inches. This is still about 80% of the combined area of the two 2 inches tubes but it is also what the JDM headers uses. And for a normally aspirated car it should be more that enough. Would this be a good, cheap, stock looking, header mod to do? Of course combined with at 2.5 inch high flow cat (or testpipe) and a Greddy PE exhast (2.4 inches diameter). What do you guys think? Has anyone tried this on their tegs? I’m thinking about giving it a shot.