Hey guys, Im putting a 4" dump pipe on my ba mkII, ive changed the cat, removed the centre mufflers and replaced the rear muffler with a high flow mercury muffler, also done some custom intake work, I had it tuned at EFI perfomance and it pulled 337 rwhp @8psi. My question is- Would I need to get it retuned if I put this new dump pipe on? and also do the wastegate flap mod aswell?. Thanks for any help

i would say its not completely necessary, but to get best results from the modifications a tune will take advantage of any changes...

YES port the wastegate and larger flapper...
Opening exhaust will create "over boost" issues...
A quick way to detonate engine...= engine damage..

get the tuner to tune in close loop & if your going to stay around the 15psi mark or less no need to do the turbo I've done this many times with absolutly no risk of spiking even with a full exhaust system replaced....... 4'' dump 5'' cat & 3.5'' mandrel bent system with a 3.5 '' rear muffler

Close loop tuning is the key unfortunatly theres alot of tuners out there that dont understand the concept & tune in full open loop & unless you have a bigger turbo & chacing 400rwkw+ its un nessasary also coming into summer close loop tuning will maintain similar power levels......the Ford BA-BF-FG computors have all of these features there, why switch them off ???...dum & unsafe if you ask me!!

Sorry to hijack or start another thread, but Im putting a gt3540r (BF XR6 turbo) on a EB with a AIT manifold etc. Just wanted to know if the BA/BF dump pipe (aftermarket 3.5") will fit in the engine bay down to underneath the car, also any idea if its worth doing the wastgate flapper mod if Im only after 300rwkw? and anyone know where I can get a aftermarket dump pipe cheaper than $350 delivered? in either 3" of 3.5"

Cheers.