I've had a muffler shop weld me a straight pipe (2") that replaced all the cats. I still have the stock catbacks. The shop also welded the split-air pipe on the straight pipe. Would this system create enough backpressure to open the fifth and sixth ports. I did not noticed a very big power gain (the precats where already empty) and at high rpm's the car seems to rev a lot slower. This would indicate that the ports are not opening, right??

My car got very loud, especially when cold, then it makes a nasty metallic sound coming from the new straight pipe. Could it be backfireing?? Was welding the split-air pipe on the straight pipe a bad idea???

Marco.

ps. the problems with the coolingsystem also still exists so these problems were not caused by a clogged cat.

 

About your only choice for fixing that problem, without spending money, is to wire open your ports now. You should gain back that top end you lost.