I need to hear from those of you that have a y-pipe and cat back.
i believe the custom y-pipe i had made for my car back in the summer is too large. the front and rear down sections are 2.25" and enlarge to 2.5" just before the cat. i have a high flow cat and b-pipe muffler. they are 2.5".

what's the diameter for the warpspeed y for both down sections and collector?
also,
what diameter do most of you guys have your hi flow cat and b-pipe at?

i don't think that the b-pipe and cat are causing my problem but i believe that the y-pipe was made too large therefore causing a loss of low end power.

the car does feel much better now that i got the manifold studs fixed last week.
i had 6 broken studs

 

You should have matched up the dia of the Y outlet to the dia of the cat input flange. Makes no sense to make one thing huge only to bottle it up again. The dia is probably not TOO bad. It's the fact that the exhaust is banging into the flange on the car. Have it cut off and have a smaller pipe put on.

 

it does match up.
the two down pipes start at 2.25" and as they come together at the collector it increases diameter to 2.5" before the hi flow cat.

btw people this a question for vg30e drivers. although, it could be possible that a ve would react the same way to a setup like mine.

 

I'm not sure what size the 2 section are of the WSP y. Though, here's my setup:

-WSP Y 2.5"
-Carsound Cat 2.5"
-WSP B 2.25" (resonated)
-Borla Turbo 2.25" muffler

I decided to go 2.25" on the rear because it tapers down nicely with the WSP b, and it's a little better for low-end since I mostly do lots of city driving.

 

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