Header Questions, Need Opinions

[Treyzian]

Sorry in advance for the wall of text...

I picked up a set of Megan headers a while back, and the rasp is really starting to annoy me. It's attached to a Borla catback, so the giant resonator helps with the rasp, but it's still bad throughout the higher RPM's.

From what I've read, the rasp comes from the unequal lengths of the runners.

I'm currently trying to decide between paying an exhaust shop to fabricate and weld on custom piping to make the runners equal lengths (rough estimate of ($400 to fabricate and weld the piping and also a high flow cat) OR just purchasing a new set of RPW's ($1000+ after shipping costs and fabrication costs, and a high flow cat).

I'm planning on a 6g75 swap this year, so I was looking more to just get rid of the rasp rather than performance right now.

Would welding on the equal length runners and high flow cat get rid of or atleast reasonably reduce the rasp?

#2 Would welding on another resonator in place of the high flow cat reduce the rasp more?

[chavezeclipse]

both would help. dont do a custom y pipe until the 6g75 as it will have to be lengthened anyways.

[Silvertune]

That's not true, unequal length primaries change the exhaust note greatly but it does not cause the rasp. Besides, the Megans have equal length primaries anyway. They rasp because they are the single shittiest designed header available in the performance world for any platform ever.

They suck for a few reasons. The primaries dump into a garbage collector that goes into a 2.5" secondary. You exhaust pulses hit this carrying a LOT of kinetic energy yet and it becomes a resonance chamber, as well as killing performance.

The other thing that sucks is that the downpipes are unequal length. The RPW shorties for instance have a loop in the rear pipe before the Y to make them equal length. Those headers sound great.

There are other reasons too but these are the major rasp contributors.

[3g4JeSuS]

Is the Megan header really that terrible, just asking cause I decided not to turbo, updated my stock exhaust to invidia n1, and planing to do a throttle body swap thanks to advice from Corey & Rivers. On Sunday I ordered a Megan header from wesellcarparts. Rivers says his sound great, so whats this rasp I keep hearing about? Thanks

[Silvertune]

You'll hear it, especially with the N1.

The problem with opinions on sound is that they're opinions. Some people think rasp is cool.

[Treyzian]

Originally Posted by Silvertune

The other thing that sucks is that the downpipes are unequal length.

That's what I meant, downpipes not runners.

And yes, if I went the route of having custom piping fabricated, it would be to follow the model of the RPW shorties.

What do you mean when you say:

The primaries dump into a garbage collector that goes into a 2.5" secondary. You exhaust pulses hit this carrying a LOT of kinetic energy yet and it becomes a resonance chamber, as well as killing performance.

What do you mean by garbage collector, KE, and resonance chamber?

[3g4JeSuS]

Originally Posted by Silvertune

You'll hear it, especially with the N1.

The problem with opinions on sound is that they're opinions. Some people think rasp is cool.

Damn so the Rpw shorties you recommend?

[Corey16]

Originally Posted by Treyzian

Sorry in advance for the wall of text...

I picked up a set of Megan headers a while back, and the rasp is really starting to annoy me. It's attached to a Borla catback, so the giant resonator helps with the rasp, but it's still bad throughout the higher RPM's.

From what I've read, the rasp comes from the unequal lengths of the runners.

I'm currently trying to decide between paying an exhaust shop to fabricate and weld on custom piping to make the runners equal lengths (rough estimate of ($400 to fabricate and weld the piping and also a high flow cat) OR just purchasing a new set of RPW's ($1000+ after shipping costs and fabrication costs, and a high flow cat).

I'm planning on a 6g75 swap this year, so I was looking more to just get rid of the rasp rather than performance right now.

Would welding on the equal length runners and high flow cat get rid of or atleast reasonably reduce the rasp?

#2 Would welding on another resonator in place of the high flow cat reduce the rasp more?

If you really want to save money just buy a good 36" resonator and have that welded on. That will eliminate a good portion of the rasp but won't eliminate it completely. You will still have rasp with the Megan headers no matter what. The RPW are absolutely fantastic and sound great. But they are very expensive. If you don't decide to buy the RPW's then do what I mentioned because that will be the easiest and best way to eliminate a lot of the rasp compared to what you were saying as far as welding on equal runners and getting a high flow cat.

Originally Posted by 3g4JeSuS

Damn so the Rpw shorties you recommend?

Rivers did say he likes his when I asked him a while back but they do provide rasp. If you wanted to save some money you could just buy a stock 2000 eclipse exhaust manifold that basically looks exactly like an aftermarket header. You could probably get one for less than $70. It performs exactly like the Megan's but doesn't produce as much rasp. It's just no a "Show" type of exhaust manifold. But the RPW's will sound excellent though and will eliminate A LOT of the rasp but they are on the expensive side. I also recommend the RPW's if you can find somewhere that is selling them.

[chavezeclipse]

even better than resonators are baffle packs. i put one a a 4 banger with 2.25" exhaust, no tell tale difference in performance but 80% rasp gone and quite a bit quieter. i believe flowtech makes them

[Silvertune]

Originally Posted by Treyzian

That's what I meant, downpipes not runners.

And yes, if I went the route of having custom piping fabricated, it would be to follow the model of the RPW shorties.

What do you mean when you say:


What do you mean by garbage collector, KE, and resonance chamber?

It would take far more then changing the downpipe lengths to kill the rasp.

Garbage collector: Garbage is an adjective. The collector is the piece that all primaries join into. It's oversized and has lots of flashing in it, perfect for augmenting exhaust pulses.

KE: Kinetic Energy.

Don't worry about the last term. You'll figure it out eventually.

[Jonny03GT]

Originally Posted by 3g4JeSuS

Damn so the Rpw shorties you recommend?

OMG yes.... I have a 74 platform..
Megans/ 3 cat delete/ invida cat back

It's too F***ing loud
I can't stand them...as soon as
i break 46- 4700 rpm.. Personally
I think its damn near unbearable

[M-Rod]

RPW or nothing IMO. Anything else seems to have an overbearing amount of rasp.

Here's one of my examples of how amazing the RPW's sound.
6G75 8G Galant with 3" GS-T Exhaust - YouTube

[Treyzian]

Alright, thanks guys. RPW's it is then.

Just to double check, both short tubes and long tubes come with the equal length downpipes right?

[Silvertune]

Long tubes no. There is physically not enough room with a long tube header setup to make equal length secondaries. That said since they are LONG tubes, that isn't necessarily a huge issue.

Besides, the shorties sound fantastic. The long tubes however are the best sounding headers you can get on these motors.

[Corey16]

Originally Posted by chavezeclipse

even better than resonators are baffle packs. i put one a a 4 banger with 2.25" exhaust, no tell tale difference in performance but 80% rasp gone and quite a bit quieter. i believe flowtech makes them

Hmmm never heard of baffle packs before, that's a first for me. I take it those work a little differently than resonators as far as exhaust flowing through them?

[Treyzian]

Originally Posted by chavezeclipse

even better than resonators are baffle packs. i put one a a 4 banger with 2.25" exhaust, no tell tale difference in performance but 80% rasp gone and quite a bit quieter. i believe flowtech makes them

Originally Posted by Corey16

Hmmm never heard of baffle packs before, that's a first for me. I take it those work a little differently than resonators as far as exhaust flowing through them?

FLO~PRO - Baffle Packs

I'm far from being an expert, but from the design they have posted on their website, it looks like it may be slightly restrictive. I think a bigger perforated core might be better as it should quiet the noise as much as the bafflepack while not affecting flow.

[chavezeclipse]

its two perforated tubes each slightly smaller than the inlet. the tubes are perforated all the way around. i highly doubt there would be any restriction and the car i put it on did not see any. just a lot quieter and no rasp. that was a 4 banger eclipse with obx longtube header, magnaflow cat (still had rasp even with that), 2.5" piping (exhaust shop used wrong size), flo pro 2.25" baffle pack, magnaflow turbo style muffler 2.25". thing is very quiet. now the baffle packs have fiberglass in them so when that blows out, then it will be a bit louder but the design should help reduce rasp. me personally, i like to use magnaflow 3 chamber mufflers. i currently have a 6g74, cmf headers, custom downpipe using 2.25" piping, going into 2.5" right at the y. then i have a flo pro resonator mounted backwards to reduce noise, a magnaflow 4" racing muffler, then a magnaflow 3 chamber muffler. no rasp at all.