APR 3" Downpipe Coupler for Milltek 3" Catback

If you want it done right...DIY

Note: Before Milltek was added the APR downpipe (cut) fit to the stock catback.

Is there a coupler that can connect these two 3" pipe ends? I believe my installer just connected the reducers from the APR and Milltek creating the "pinch" between the two 3" pipes. Making me sick that I didn't DIY.

The APR end of the connection is out of the photo frame, but trust me, the APR downpipe is 3".

For gods sake please don't tell me I need to buy a new downpipe. addle:

Remove the slip fit clamp from the APR side. Cut the Milltek exhaust right at the weld where it tapers down. Buy a 10" piece of 3" stainless exhaust from like Summit Racing. Have a exhaust shop fit and weld the piece in to just one side, then connect the two 3" exhausts using a new (have to buy) 3" to 3" slip coupler.

I have a similar situation. APR 3", tapers down to 2.5", then back up to 2.75" (AWE cat back). Doesn't bother me though.

Is the restriction causing any losses? This is my first catback, so I want to make sure I'm getting all the gains for the money invested.

The slip fit clamp on the Milltek side. I don't think the Milltek side is tapered. I think that is just the coupler that is tapered up to the Milltek pipe. Please see the first post with photo attachment drawing (titled "Untitled-2.jpg).

Thanks.

Don't worry about any power losses from the reduction. It's barely there and only people who want to brag about dyno numbers should care. If it's not leaking and everything lines up on the car, just let it be.

I've had to deal with mating 2 different branded parts a few times. It's a huge headache. Different downpipes come out at different lenghts and angles. Which in turn cause alignment or fitment issues with your cat back side. I had a Milltek CBE that came off of a full TBE so it didn't have the reduction adapter. I bought the Milltek reduction pipe only to find that it protruded too far forward to fit my AWE downpipe. Solution was to scrap the adapter or trim the AWE downpipe end. At this point I was so frustrated and done with it that I cut the AWE end. Ruining the resale value of the downpipe.

If you want to go full TBE, I would sell the parts you have off and buy a full TBE that was designed on a test car as one system. Or live with either downpipe only or CBE only. A little hassle early on but worth it in the end.

Some much more to it than simply connecting the ends of two 3" pipes. Thanks.

I'll keep it in place. I think getting upgraded engine and transmission mounts at the same time wasn't ideal. So much has changed about the ride is a bit shocking, but I know I'll get used to it.

http://m.summitracing.com/parts/wlk-41892
Mild steel 3" id coupler

If I'm right the shop I went to cut the downpipe and the adapter and welded the adapter to the downpipe and make it 3" all the way.

I wouldn't worry about this.... everyone who buys separate catback and downpipes have the reducer (including myself). I thought about having it corrected for a straight through 3" but it isn't worth the money to me for maybe 1-2hp if that.

I ended up having my APR DP cut and welded to my CTS cat back. Love it

Thanks everybody! With such a big change and never hearing it before it has been a bit of a challenge to get use to. It could be that I've also added engine mounts, transmission mounts, diverter valve, master bracket brace, K04, and dog bone kit. It's a TOTALLY different car now. Lots a rattling due to engine mounts, and catback.

At low RPMs the catback sound a bit weird, but when it gets above 50 mph, with higher RPMs is smooth as silk. Well, also the back seat delete makes a bit of difference as well.

Again, thank you everyone for your messages. It's helping me feel much better that the coupler isn't a big deal.

- Scott

lilfleck said:

I wouldn't worry about this.... everyone who buys separate catback and downpipes have the reducer (including myself). I thought about having it corrected for a straight through 3" but it isn't worth the money to me for maybe 1-2hp if that.

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This. OP if your exhaust fits fine with no leaks then dont spend time fixing it. Its not worth the hassle. I cutted mine because the previous owner welded an extra 3" pipe on the downpipe so I just dont want to mess them so the shop just cutted the catback reducer and make it to a full 3". There is one clamp on the catback.

escottc said:

At low RPMs the catback sound a bit weird, but when it gets above 50 mph, with higher RPMs is smooth as silk. Well, also the back seat delete makes a bit of difference as well.

- Scott

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I'm telling you, I changed two downpipe because I thought there was a leak somewhere, but the shop tried to find the leak but it was not there. I think its the way our car sounds after a removing the OEM downpipe. Since the OEM DP restricted the air flow so we dont get that sound.

@The Unholy, It does sound friendlier with the EOM pipes for sure. Without the backseat, spare, foam rubber stuffing, and carpet covering deleted the sound is almost intolerably loud. Have a 3-4 hours drive in the next week so I look forward to getting my back seat delete covering.