Best Test Pipe option for swapping back to stock

[850tgul]

Looking at going the test pipe route but would definitely need to be able to swap the primary cats back in each year for inspections. Looking for a solution that would allow me to simply bolt the cats back in. Read many threads on this and while the question of reverting back to stock was brought up there didn't appear to be a definitive answer as to which brand of pipes allowed for the easiest swap. It seems many of the TPs require cutting too close to the primary cats to provide enough pipe to clamp them back on.
Is there a TP brand out there that, by design, allows the stock primaries to be bolted back in after they are cut out? Thx

[xwilkinx]

I don't think it's dependent on the test pipe brand, but more so the initial removal of the cats. If it's a clean cut then the cats technically can be welded back on. Still a big hassle though.

If you plan on swapping back and forth frequently you should get a catless x-pipe. Makes swapping to stock easier since you won't have to cut/weld cats every time.

[850tgul]

Yeah, I am definitely not looking to have them re-welded each time. I was hoping to be able to just put them back on with the same clamp the TP use.
Catless x-pipe or maybe picking up a stock x pipe and cutting that up may be the way to go.

[eatsleepboost]

Originally Posted by 850tgul

Yeah, I am definitely not looking to have them re-welded each time. I was hoping to be able to just put them back on with the same clamp the TP use.
Catless x-pipe or maybe picking up a stock x pipe and cutting that up may be the way to go.

Yup. This is the answer.

[derbo]

My original plan was to do the same. It really doesn't matter which test pipe you use as you will be modifying it. I didn't want to buy catless pipes due to storing a full x pipe is very cumbersome.

Your best bet is welding VBands on the test pipes, cats, and rear exhaust part. This requires 6 Vbands, 2 Vband clamps.

MotorIQ had a nice article on how they did it.

https://motoiq.com/project-e90-m3-pa...xhaust-tips/3/

[850tgul]

Originally Posted by derbo

My original plan was to do the same. It really doesn't matter which test pipe you use as you will be modifying it. I didn't want to buy catless pipes due to storing a full x pipe is very cumbersome.

Your best bet is welding VBands on the test pipes, cats, and rear exhaust part. This requires 6 Vbands, 2 Vband clamps.

MotorIQ had a nice article on how they did it.

https://motoiq.com/project-e90-m3-pa...xhaust-tips/3/

good stuff, thanks

[derbo]

Originally Posted by 850tgul

good stuff, thanks

No problem! I spend a good amount looking for a solution for myself as I dont have space for storing a stock pipe.

Pros:
smaller footprint for storage (vband cats vs full x pipe)
easier to remove and replace for emissions testing

Cons:
Requires welding from a reputable shop
almost cost $400 or so in parts. Labor will vary based on your location.
Might be a good idea to buy extra O2 sensors to make swapping easier as well.