M52 Swap – Exhaust Sounds Like Crap

[Boardhead]

I just got my M52 swap in my 90' vert on the road and it performs way better than I had expected. It really wants to RUN from 3500 rpm to redline! It is a blast taking it out on damp pavement here in Florida and intentionally spinning both rear wheels in first thru third gear with my 14" Basketweaves and skinny tires. However, I am really disappointed with the exhaust note. It sounds like a crappy four cylinder at anything above 3k rpm when under load (combination of raspy and load metallic noise). Here is my set-up; I am running ebay headers with dual 2” pipes to a dual-in-dual-out cat. From the cat I have dual 2” pipes necking-down to the dual ~1-3/4” dia. stock cat-back. The photo shows my home-made custom set-up. Excuse the poor welding, other than my rear sheetmetal repair, this is the first substantial MIG welding that I have tried.
My objective is to keep the deep throaty sound that I have under 3K, all the way through the power band. Loud isn’t necessarily bad as long as it isn’t “buzzing”. I have searched this forum for others that have tried similar set-ups but haven’t found the right combination that builds on what I currently have. I am sure some of you guys have tried this setup and have found a sweet sounding solution. I appreciate your help!

[jakeb]

I was running ebay headers when I first did my swap and yanked them fairly quickly.

I had mine Y'ed into a single pipe and thought that was what was causing a lot of the rasp but I am pretty sure it is from the ebay headers..... The SS is thin and causes all sorts of noise.

Maybe add a resonator after the cats.... or yank the ebay headers and get a pair of welded up obdII manifolds.

[Boardhead]

Thanks for the input. I was hoping I would not have to pull the ebay headers, but if that is what it takes… I think I will first try adding resonators as you suggested. Any recommendations on manufacturer/model?

[Dominic49]

i have my headers coated and it reallly cuts down on the rasp

[e30polak]

Ebay headers are thin and tinny. That is a main cause of the rasp.

[Boardhead]

Is header thermal wrap effective in reducing rasp?

[FredK]

Hey, that doesn't look half bad for a first exhaust! I couldn't even imagine doing a dual in dual out for my first exhaust.

You should have seen my first MIG welded exhaust. The welds were lumpier than the mattress in a 29 dollar a night motel.

[hugh jass]

you can really use any small universal muffler as a reasonator. that would be a cheaper option than yanking your headers.

[e30this]

OBD2 headers welded and wrapped.
dual 2inch pipe into a dodge magnum converter. (its dual in 2 inch single out 2.5 inch)
2.5 inch all the way to a flowmaster 40 series muffler.

I have had about 4 different exhaust setups with my swaps and by far this is the best one yet.

[e30polak]

Here is my exhaust: eBay headers> y-pipe > 2.5" piping> generic Borla 2.5" muffler > 2.5" piping> 2.5" Vibrant Street Power muffler

http://www.youtube.com/watch?v=nS2RJCk_itY&feature=related

http://www.youtube.com/watch?v=r2H5YreLZqk

It's all about the mufflers and resonators you use to compliment the headers. I made the rasp work to my benefit. :D

[e30s50dan]

are your headers wraped ?

[Wh33lhop]

OBD2 headers welded and wrapped.
dual 2inch pipe into a dodge magnum converter. (its dual in 2 inch single out 2.5 inch)
2.5 inch all the way to a flowmaster 40 series muffler.

I have had about 4 different exhaust setups with my swaps and by far this is the best one yet.

...

To each his own.

[e30this]

...

To each his own.

Please explain, Maybe you like a shit load of rasp or sounding like a honda with a fart cannon on it.

[Wh33lhop]

Please explain, Maybe you like a shit load of rasp or sounding like a honda with a fart cannon on it.

Yes, I want my BMW to sound like a 4 banger. That's why I bought a 325i.

You will note I didn't talk down on you, merely stated my opinion. I like exhausts that don't drone. I am sure it's loud as fuck but it doesn't sound good to me, not really a fan of the lift-off snarl either. Inline 6s should sound smooth if you ask me.

Just my $.02.