Speed Engineering

iTrader: (35)

Thank you for your business.. We know the Y-Pipes are close to the drivelines on the 99-06 4wd trucks, but it should clear just fine with a good set of motor mounts. We actually just revised out 99-06 Y-Pipe last week to fit the 4L80E transmissions. At the same time we dropped it down a little for the 4wd guys, and added a O2 bung for wideband tuning as well. That prototype was just sent off. It will be at least 6-7 months before we have a batch of those on hand.

As for the headers, we have been selling those for the 1999-06 4wd trucks for several years successfully. The only thing that I can think of is that your Avalanche might have a little bit different chassis than the silverados, or maybe the front diff is a little different. I am honestly not sure. Either way if you are not able to make them work you can always send them back for a full refund.

Thanks
Sean

Formula96

I really wish they fit, would love to be on the road. The motor mounts are brand new Delco from the Chevy dealership, so that's definitely not the problem. There is no way to make them fit without really messing them up so I guess I'll get another set coming and send yalls back for a refund. Hate it's turning out this way.

Ray Finkle

So do these current y-pipes not work with a 4l80e? Or is it just a little close and may need some "massaging"? I swapped a 4l80e into my 1500, that's why I ask.

Speed Engineering

iTrader: (35)

Yes, same here. We never like to hear of customers having fitment issues, and continuously try to improve our products as we come across the issues. That is one of the reasons why we just resigned our 99-06 y Pipe. I sorry to hear yours is hitting in so many places. Not really sure if its because its an Avalanche, or what might be the issue. I will personally check everything out when they return.

Thanks
Sean

Speed Engineering

iTrader: (35)

Ray Finkle: Our 99-06 Y-Pipes are designed for the 4L60E transmissions at the moment. You can make them work fairly easily with the 4L80E, but modification will be needed with our current design.

Thanks
Sean

Mconcha

iTrader: (1)

Might be a prime opportunity to test these on another Avalanche to either:

A.) confirm they won't fit and make note on your site, so no one else goes through the same hassle and frustration or..

B.) prove it was this customers specific Avalanche that was the issue (no offense to the OP).

Seems like you guys have great customer service none-the-less.

Formula96

Not the OP so i can't get offended lol. Would like to know for sure. I do remember one thread i came across not to long ago about a person having the same problem on a silverado but they refused to try motor mounts? I'll see if i can find it...

GM1697

iTrader: (1)

mine nailed the driveshaft in my truck, had to modify it. Used the extra piece they include for 07+ trucks. Pics below.

I've said it before and I will say it again. Even if the motor mounts were collapsed, replacing them would make this fitment worse because it would raise the motor up, thus raising the y-pipe into the driveline even more. These y-pipe's are simply poorly quality controlled. Sean from SE disagrees with me and offered no replacement.

FFDP

iTrader: (2)

It's hard to quality control something when they may be coming from like china and take 6-7 months to get your design back.......

Ray Finkle

I just installed my speed engineering 1 7/8" long tubes on my 03 5.3 with a 4l80e swap. I had to dent the y-pipe in 1 spot below the trans pan and 1 little spot on a primary on driver side by the frame. Other than that, they fit perfect.