Ok, so I have commented on a few other threads looking for a little info, but am not getting what I need. Here's my situation and here's what I need to figure out; (Mods I have put past ? in the exhaust section, but doesn't seem to get responded too, plus it's sedan specific)

I recently bought some used FI HFCs to put on the stock exhaust, but found out once I got them that they are 2.5" for the coupe rather then 2.25" for the sedan (what I have). I do not like the idea of mating the 2.5" HFC to the OEM 2.25" y pipe and have that "lip" at the mating surface. Just seems to not be good for flow whatsoever. So I have come up with a few different options. (Slightly concerned with rasp)

1. Just use them anyway as is (technically only 1/8in lip all around)
2. Add a 2.5" Y-pipe (conflicting stories that makes rasp worse)
3. Add a 2.5" y-pipe with resonators (sent an e-mail to exhaust depot to see if he can do it)
4. Sell off the HFC and just get a y-pipe leaving OEM cats for similar gains, no rasp, but less sound improvement
5. Sell HFC and just get Sedan HFC

BTW I do NOT want to do a full Cat Back, so don't suggest it.

 

5. Sell coupe HFC and buy a sedan HFC. (suggest Berk HFC's)

Not a technically qualified response, but it just makes sense. I find stuff all the time that I want for my car but I find out it's for a coupe and I pass on it. You're gonna try to modify something to fit a sedan that it wasn't made for. Just seems like a bad idea.

I don't like the idea of the new y-pipes because they will increase the rasp if you decide to add the HFC's later.

Just my suggestion.

 

5. Sell coupe HFC and buy a sedan HFC. (suggest Berk HFC's)

Not a technically qualified response, but it just makes sense. I find stuff all the time that I want for my car but I find out it's for a coupe and I pass on it. You're gonna try to modify something to fit a sedan that it wasn't made for. Just seems like a bad idea.

I don't like the idea of the new y-pipes because they will increase the rasp if you decide to add the HFC's later.

Just my suggestion.

 

It's not really modifying something to fit that's not suppose to in a sense. Just that they made the sedan 1/4" smaller exhaust to keep it quieter and also the reason it's rated a few horse lower. So uping the exhaust to 2 1/2" is actually a good idea.

Not against your response, just saying it's not like taking something completely not made for the sedan like suspension or say a body piece, just enlarging the exhaust which is a size already used with this motor.

 

Ugghh... bump. Really? No one?

 

Why can't you just use some bigger gaskets? I'm sure it's be more than enough to cover the 1/8th difference. Unfortunately, I've gotta go with 4dr. It's just a big headache (IMO). I was thinking "get an exhaust system," but then you'd still run into the same problem. I never knew there was a difference in the two sizes by the way (thanks for the information). Just sell 'em dude...they'll go QUICK!

Good luck dude!

 

Adding a Y pipe will not make your car raspier. I did that on my sedan. I also have hfc on my car as well but then upgraded to en entire catback system. I don't know about fast intention but berk hfc are very raspy. I have kinetics and they are not raspy at all. If I were you just upgrade to a 2.5" y pipe; tanabe or megan and call it a day. The coupe and sedan share the same y pipe only difference it that the coupe's is larger.

 

How was it before the cat back upgrade?

 

I am looking for the same thing. Please post when you hear back from Exhaust Depot about the y-pipe. I was also thinking about HFC + magnaflow x-muffler replacing resonator section. It kind of sucks to have to chop the stock exhaust just in case you sell the car in the future.

 

sell them and get the HFC for the sedan

 

UPDATE - I have since bought an Exhaust Depot Y-pipe and installed it. The HFCs are still not installed. Y-pipe has some gains I guess, nothing noticeable in sound.

Still having the debate on whether I should install the HFC and possibly have rasp (?), or possibly lose low end power (?) OR sell the HFC, not worry about the headache, and get R2C intake?

Whatcha think?

 

The megan y pipe has has a 3 in outlet and the stock mid pipe has a 2.5 in inlet or smaller. Is that a problem? your going from air flow from 3 in to 2. something in. I ordered my megan Y pipe but this was a concern for me? Does any one have any feedback on this? I know people have used this set up any issues?

 

are you sure sedan HFCs are smaller than coupe HFCs?

 

https://www.myg37.com/forums/private...flow-cats.html