Quote:
Originally Posted by smg1138
If I end up switching to the JDL 4-2-1, would it be worth upgrading my overpipe too? Wasn't sure how much gains could be had by changing it, but it seems like removing the stock piece is a PITA.
Current exhaust setup: JDL UEL catless header > stock overpipe > stock frontpipe > Perrin resonated catback
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I had similar questions... Here were my questions and answers from JDL:
1. Which front pipe would you recommend for the most power in an NA application? 2.5" or 3" test pipe?
There's really no difference in power between the "Test" pipe and any resonated version. However the resonator(s) will add some weight. I personally haven't seen much of a difference in power levels between the 2.5" and 3" on na testing. The 3" makes slightly more top end while the 2.5" is stronger in the mid range. Nothing major though.
2. Any idea roughly what the power gain difference is between the test pipe and catted front pipe? Or are there any gains with the catted front pipe?
No cat is worth 3-4 horsepower from what I've seen. To be honest the cat that comes in our front pipe isn't recommended for track or autox use. I do have an option for a motorsports use cat that is rated for high heat and horsepower however it is quite a bit more expensive. If you can run without a cat it's what I would suggest.
3. Over pipe - any idea of power gains with this, or about the same as stock?
Definite gains with a header, especially ones where the merge collector is located near the overpipe connection. The overpipe essentially becomes an extension of the merge collector at that point so making sure the diameters are match and flow is smooth is important .