Question About Performance of GT Exhaust on 3.7 (2.5" vs 2.25")

[JStang93]

I've read through the big thread about doing this - and my question is this. Car has BBK shorty headers and factory exhaust. Looking at a Borla Type S CAT Back - and they stick with the same 2.25" pipe diameter as factory and it's $1500...why do they not increase pipe diameter like the do on GT systems??

Alternative is swap in a factory GT Cat Back (increasing to 2.5" pipe diameter) and see how we like it and maybe change axle back later to tweak sound. Seems like going to larger pipes would be good - but Borla doesn't do that in their design - is that because 2.25" is optimal for 3.7 V6 performance?

I can pick up a pull off GT cat back for $150 - which sounds really appealing vs $1500 - but don't want to decrease performance of the car as a result.

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[Emilbadal]

I think there are couple of reasons that I think Borla is sticking with 2.25" pipe.
1- main reason, when you increase the pipe diameter you introduce drone. I have the stock GT exhaust and the tone marginally creeped into being droning territories...not bad though
2- the 2.25" pipe diameter is enough for the NA 3.7 and increasing it doesn't help much

As I said, I have the GT catback with Ford Racing by borla sport axlebacks. If I knew what I know now, I wouldn't bother with the GT catback, I'd get the axlebacks only if I couldn't swing for the borla catbacks.