I currently have a 3"dp to a gutted kitty and then the stock 3 1/2" exhaust out. How much benifit will their be to going to a 4" exhaust. Also got a tymar intake. I mostly tow with the truck. Any opinions on what would be the best thing to do. I want to hear more turbo!!

 

With a 4" exhaust and a Tymar you will definately hear the turbo a lot more. It will also help keep the EGTs down.

 

I installed the 4" downpipe on my 99 and It actually made the turbo hizz inside of the truck quieter but outside through the tail pipe it was louder. Also check out the thread below for info on the downpipe. You might concider a smaller downpipe depending on the application you use your truck for.

https://www.ford-trucks.com/forums/s...d.php?t=241393

 

With the 4" your turbo will spool up quicker and egts a few degrees lower.

 

With the 4" my turbo spooled up slower than with my stock 3".

 

I lookin for a 4" exhaust that will bolt up to my 3" dp for a good price. Any suggestions?

 

There is a system by walker/Dynomax. It bolts up past the polution canister and rear intermediate pipe. You can get them at Advance Auto Parts for pretty cheap. You can also get the upper and lower intermediate pipe from Advance 4" but will have to find a reducer that goes from 4" to 3" plus there is a flange on the end of the downpipe that would need to be cut. I am currently working on my 99 year 3" downpipe to go to 4". You might to double reduce the 4" to 3 inch working in half in steps. If you would recommend just going 4" back like the dynomax system if you are going to keep allot of the engine stock.

 

I try not to sway peoples decisions when it comes to their vehicles, however I believe it is in your best intrests if you are going to go with a 4" exhaust in the first place to seriously consider at the least a 3.5" DP. The 3" stock DP is so restrictive that you would never see the potential of the 4" system the rest of the way back, and for the cost of the DP vs. the improvement, it would definately be worth it. I believe you should do whatever you are comfortable with as it is your truck, but i would suggest the DP changed if you are going to do anything with the rest of the system. To answer questions about price, I don't know about any DP back systems, but I got my diamond eye for 320 delivered. It also came with a 5" polished SS tip.