I've seen (only, but still) two posts saying that adding a Y-pipe to the header, cats and OEM REAR-SECTION combo results in a big loss of TQ. Haven't seen anything else about this, as most people run an aftermarket rear section with headers, cats, Y-pipe.

I'd really like to hear from people with specific experience, but short of that I'd still like to see opinions as well.

I have MREV, headers, cats and a Y-pipe that I'm anxious to install. I have a reducer cone to be welded onto the OEM rear-section, but I hate to do that, or even install the Y-pipe, if it's going to negate the TQ increase from the MREV.

Thoughts, experience, opinions?

 

Just talked to a friend of mine at Magnaflow this last
week about this very same thing. Most of the y-pipes
on the market are 2 1/2" pipe into a 3" collector, this
is as large as you want to go or you'll lose torq.
My new y-pipe is on the way since I'm going from a
Borla system to Magnaflows new single pipe cat-back.

LOL

 

i wouldnt be worried about losing anything with all those mods.........my exhaust is y-pipe back exhaust and i didnt feel any loss

 

i've also read many posts that changing the y-pipe, but leaving stock y-pipe forward, results in signifigant losses down low and minor gains up top.

this was one issue i researched indepth before making my decision

PLUS (and this is only my opinion, but it's something i've noticed) that it seems that people w/ aftermaket cats + stock y-pipe do not seem to have as many problems w/ cats cracking as aftermaket cats + aftermarket y-pipe. maybe it's because aftermarket y's don't flex as much, i don't know, but it has been a very prominent trend that i've noticed.

 

pre headers and 1/2"plenum spacer was 245whp and 245tq.....identical numbers, weird.
post dyno showed 257whp and SAME 245tq......

same dyno(dynapak), temp and humidity was similiar,......i was actually expecting a little more of both, but those are the numbers........i'm guessing now that my intake/exhaust is too much free flowing?