Completed the Cats for my Coyote - straight pipe modification

[Jester]

I recently sourced a set of stainless steel Mini high flow catalytic converters (Pypes performance exhaust) to be spliced into the stainless steel straight pipes between the headers and the SS side pipes.

I wanted to reduce emissions as well as reduce the DB's from the exhaust (at hwy speeds). Should be little impact on HP & performance (if any).

This should do the trick - see attached

SS Strait pipe & SS Pypes Mini Catalytic converters_complete.jpgSS Strait pipe & SS Pypes Mini Catalytic converters_before installation.JPG

[ClemsonS197]

I wish the FFR j-pipes for the Coyote looked as good as yours. Well done.

[DaleG]

I wish the FFR j-pipes for the Coyote looked as good as yours. Well done.

Mine are really nice, chromed. Not using them.

[Jester]

Update

Thanks Clemson - I made the j-pipes before FFR had theirs completed. I modified a set of 4.6l SS J-pipes that FFR provided. Actually quite easy to fab and the result is less restrictive than the FFR J-pipes. The resulting j-pipe/cats are quite nice as well. The welder created a jig to insure proper orientation / alignment of each pipe before cutting and welding in the cats

I installed the modified j-pipes/cats and they fit exactly as I wanted - look great as well (O2 sensors are the same location as before the cats were installed).

I started and revved the engine (in my garage) and the exhaust is definitely cleaner and the "harshness" (if that is the correct term) from the exhaust note seems to be reduced - may be related to a reduction in DB's ?? (out in the open air this may be even more noticeable). I need to do a road test to determine if I still need ear plugs but the weather is not cooperating. I also rotated the tips of the SS exhaust by 60 degrees (towards the ground). I believe the combo of the cats and rotated exhaust tips should have the desired outcome to make the driving experience even more enjoyable.

[Jester]

Ok, it's been a very long Winter that just does not want to let Spring in but today the sun briefly appeared and the temps increased to the mid 40's and I took my roadster for a short trip to road test the pipes with the new cats installed. There is a distinct difference in the db's and the harshness of the exhaust note is reduced at idle and at hwy speeds. Should make longer drives even better

[Jester]

Update

The weather is finally cooperating and I have been able to take the roadster for several long drives over the past few weeks. Some of the roads still have remnants of winter (locally sandy) so hooking up the coyote's full power to the road was not possible but very fun drive. The exhaust note is much reduced and the driving experience is completely different from last year while in gel coat (before I modified exhaust) - now it is more civilized. The modified exhaust is much easier on the ears although still has that aggressive growl when pushed. Harshness of the exhaust is gone and no ear plugs needed!

I drove on the highway for approx 1/2 hr., with traffic moving at 80 mi per hour and absolutely no issues re excessive exhaust noise - No ear plugs needed and my head was not ringing / no headache after the drive. Where as before the exhaust modifications the pipes were so loud that it was not pleasant to drive for longer periods at hwy speeds even with ear plugs (could not hear anything but the pipes) and I would have a headache after driving.

Note: although my main goal of reducing side pipe noise has been achieved, by installing the cat's the emissions have also been reduced. I believe this solution is less expensive than replacing or modifying the side pipes alone to achieve a similar deduction in DB's.

Fantastic car!

[BIGxPAPPA]

Thanks for taking the initiative. I have seen a lot of coyote admirers or owners post that they are looking for a cat solution for registration issues. In New Jersey i have the same issue. I plan on placing my order in a few months but still need to make an engine choice. Let me rephrase that, i have chosen the coyote but the state regs are so that i must have a cat on at the time of registration. Whether the cats stay on the car is yet-to-be determined, but right now i am most concerned with making it road ready. It looks like you did the modification yourself but considering i have no welding experience would it be possible to purchase a set from you?

[Jester]

Thanks for taking the initiative. I have seen a lot of coyote admirers or owners post that they are looking for a cat solution for registration issues. In New Jersey i have the same issue. I plan on placing my order in a few months but still need to make an engine choice. Let me rephrase that, i have chosen the coyote but the state regs are so that i must have a cat on at the time of registration. Whether the cats stay on the car is yet-to-be determined, but right now i am most concerned with making it road ready. It looks like you did the modification yourself but considering i have no welding experience would it be possible to purchase a set from you?

BigX - thx for the comments.

I am builder/owner/enthusiast (first build) and I installed the cats for personal reasons as there is no such emissions requirement where I live. I am not a welder either however I simply took the cats to my welder and had them spliced into my J-pipes. I would have used the FFR supplied J-pipes but they were not completed in time for my build. You could simply have similar cats cut and welded into the FFR supplied J-pipes by a local welder in your area - this may be the easiest solution. This is not difficult as long as the final J-pipe/cat retains the original length and flange angles as the J-pipe (before cutting). There may however be other Forum members in the position to supply a similar J-pipe/cat for this application as there will be many coyote builders with a similar need. You may want to ask FFR as they initially indicated they would be developing a set of Cats to fit the Coyote.

Note: I assume these cats will meet emissions compliance requirements however this needs to be confirmed - check with manufacturer for compliance for your state.

Good luck

[ClemsonS197]

Jester,

The J-pipes you used have a smooth radius instead of a choked down 'corner' that FFR supplies. Yours is a much better design.

Also, last time I spoke with Jesper he stated FFR had no intentions of making cats at this time (which directly contradicted what Dave Smith said on PowerBlock).

Stainless Headers was seeking input on the need for a header with integral cat for these cars. Give them a call.

[Jester]

Jester,

The J-pipes you used have a smooth radius instead of a choked down 'corner' that FFR supplies. Yours is a much better design.

Also, last time I spoke with Jesper he stated FFR had no intentions of making cats at this time (which directly contradicted what Dave Smith said on PowerBlock).

Stainless Headers was seeking input on the need for a header with integral cat for these cars. Give them a call.

Clemson,

Yes, I specifically fabricated my J-pipes (from a set of 4.6 J-pipes supplied by FFR) to have good flowing open radius's. At that time FFR was in the design stage re their J-pipes for the Coyote and I did not want to wait for their solution. I am not sure if the FFR J-pipes flow any better or worse than the ones I fabricated however I would guess that there would be little difference noticeable behind the wheel. I would not hesitate using the FFR supplied J-pipes and splicing in a set of Cats.

One difference re the j-pipe radius may be that I used 1/2 inch aluminum plates between the engine mounts and frame to lift the engine allowing more clearance for the for j-pipe resulting in better radius's and provides better ground clearance for the after market oil pan. I think at the time, FFR was also looking at adjusting the engine height and they may have opted for less height adjustment.

Perhaps FFR should redesign the Coyote J-pipe radius's incorporating the 1/2 inch engine mount spacers plates to accommodate more open radius's which would encourage builders to use the FFR j-pipes -FFR hint hint.