Front pipe/over pipe question

[Jmk91]

So I’m looking to get JDL front pipe/over pipe combo. I’m not sure what size to get it in. I have a jdl header and a greddy sp 2.5 cat back. Eventually I do plan on going FI. Should I get the 2.5 or get the 3 inch piping?

[Joveen]

If you're going supercharger just go 2.5 or if turbo it depends in my opinion. Maperformance turbo kit uses a 2.5 diameter downpipe. Ptuning turbo kit uses factory or aftermarket header.

Also while you're NA 2.5 all the way back will be more give more low end torque.
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[AKITA]

Originally Posted by Joveen

If you're going supercharger just go 2.5 or if turbo it depends in my opinion. Maperformance turbo kit uses a 2.5 diameter downpipe. Ptuning turbo kit uses factory or aftermarket header.

Also while you're NA 2.5 all the way back will be more give more low end torque.
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Is that true?!?!

Originally Posted by RedLeader

As with most all NA cars, the more you open the exhaust, the more low end torque you lose. Exhaust back pressure helps scavenging, which is why going to a less restrictive, wider exhaust pipe in an NA car (from the 2.25 factory to a full 2.5 with no cats, resonators, and all straight through mufflers) will gut your low end but give you a much better top end.
It IS odd that you can feel it after a single piece, but not impossible. Rumor has it that it takes a 10hp/10 ft-lb change to be noticed, but I've never tried it.

Funny this guy said the exact opposite. But that aside I think most agree and from what I know about exhaust, you tend to shift the band up a little at the expense of low end torque in NA vehicles big V8s included. but to be honest overpipe/frontpipe alone will not show you much if any change because of stock hdrs and stock tune. I've got tomei hdr, overpipe, AVO high flow catted front pipe, borla catback (2.5 all the way).. You wanta know what difference I can feel the most ? The tune! (notice not listed in the names of cool exhaust pieces) Then the headers.. the rest is just really sound and future setup for not to distant FI install. (I hope) Get the tune .. first. Piece the rest if need be to budget, hdrs first if you're gonna do those.. otherwise get a cat or axle back exhaust you want and move on and leave the rest.

[Jmk91]

Originally Posted by AKITA

Is that true?!?!



Funny this guy said the exact opposite. But that aside I think most agree and from what I know about exhaust, you tend to shift the band up a little at the expense of low end torque in NA vehicles big V8s included. but to be honest overpipe/frontpipe alone will not show you much if any change because of stock hdrs and stock tune. I've got tomei hdr, overpipe, AVO high flow catted front pipe, borla catback (2.5 all the way).. You wanta know what difference I can feel the most ? The tune! (notice not listed in the names of cool exhaust pieces) Then the headers.. the rest is just really sound and future setup for not to distant FI install. (I hope) Get the tune .. first. Piece the rest if need be to budget, hdrs first if you're gonna do those.. otherwise get a cat or axle back exhaust you want and move on and leave the rest.

Yeah I have a tune, I’ve had one for a long time haha. I did the basic oft tune than I paid steve99 for a better tune. I was just wondering for my exhaust what route to go. Last thing I want to do later on is rebuy. I’d rather do it once and call it a day. That’s why I use quality products. I’d rather pay the premium than save a few to spend a lot more later on. As stated I already have headers and a cat back. Was just wondering for front/Op.

[AKITA]

Originally Posted by Jmk91

Yeah I have a tune, I’ve had one for a long time haha. I did the basic oft tune than I paid steve99 for a better tune. I was just wondering for my exhaust what route to go. Last thing I want to do later on is rebuy. I’d rather do it once and call it a day. That’s why I use quality products. I’d rather pay the premium than save a few to spend a lot more later on. As stated I already have headers and a cat back. Was just wondering for front/Op.

like already mentioned.. performance not that noticeable for me.. better tune like Steve's maybe but probably not .. might save some weight as well.. sound will change for sure

[tomm.brz]

anyway VVT can help recovering a bit of low end torque if going large with exhaust pipes diameter, by reducing overlap between valves