Yeah, but I also will have to get a new intake pipe. I've been using the perrin intake/filter with the MAF still in place even though I have been on speed density for a long time now.

Is it really that beneficial to run a 4in pipe with a reducer down to 3.5in at the turbo over just a 3.5in throughout pipe? Would the pressure increase at the 4 to 3.5 neck down not negate the gains of having a 4in pipe over just the 3.5 all the way?

I mean I actually would like to just run the 4in pipe because my perrin filter inlet is (4.5in IIRC), but am just curious?

 

Yeah I also wanted to run Perrin's filter and saw that they also have a 4.5" ID filter, but I honestly feel that a 4" intake pipe and filter I am running is helping power wise in conjunction with the FP housing. I also asked them before I made my 4" intake if they would be willing to make a 4" ID filter, but they refused.

 

Find a friend that has a nice sized lathe. Have em make a nice little velocity stack that will step down from 4.5" to 4". If I go the big intake route this is what I plan on doing.

 

I bought one today. Switching to speed density to make the most of it. ... going to be a new learning curve all over again. stock turbo too...

 

^^ you are going to like it, It's worth evey penny.