Anyone tried a 3" & 4" exhaust combo

[TREEMAN]

Just put in a PDR HX35 14cm turbo before I installed a 4" exhaust & was pleased to see that there was no turbo lag ,however as soon as I installed the 4" exhaust I noticed quite a lag in spool up & a lot more smoke if I get too heavy on the foot coming out of the hole. As there is less back pressure with the 4" I was considering welding on a 3 to 4" flare on the 3" downpipe & swapping out just that section to try & eliminate turbo lag. Curious if anyone has tried this & if so what were the results. Iwas hoping for a quicker spool up with the 3" & the lower egt,s with the 4" The best of both worlds .

I plan on replacing the EZ with the comp which I understand will control the smoke to a certain degree.

Also i,m only seeing 25lbs of boost & thats with the boost elbow installed. Did any of you guys mess with wastegate setting at all to achieve higher boost. If so which way did you screw the wastegate rod .

Thanks in advance & Happy New Year to all

Ian

 

[Kimrey]

Treeman, See sig on what I have. I went 4

' from res. back. A K&N air filter will also help the spool up on the turbo ( more air quicker). As far as the elbow, screw in more boost, out less boost.

 

[TREEMAN]

In reply to my own post ,I replaced my 4" down pipe with the 3" & flared it out to the 4" half way between the first hanger & the muffler. Results arent quite as good as I,d hoped but a definate improvement in turbo lag. The egt,s are a little higher but tolerable,but seems to have a much deeper tone audible in the cab which I really like. Will have to see how she does when I tow & also when the comp goes on.

Ian