FAQ - Frequently Asked Questions Evo X Test Pipes (Test Pipe, Resonated Test Pipe, Mini-Muffler Test Pipe) Q - Will I get a Check Engine Light (CEL)? A - All of our cat replacement pipes comes equipped with our own unique mechanical "CEL Fix". It is designed to keep the secondary oxygen sensor out of the direct flow of exhaust. This method is effective at avoiding the P0420 (catalyst inefficiency) CEL, however, it is not fool proof. We have some customers with over 30,000 miles with no sign of a P0420 code. Some users have still reported that they received a CEL over time. From experience, 9 out of 10 customers are pleased with their purchase. Q - Do I need gaskets? A - You don't necessarily need to install gaskets, but you do require something for flange sealing. We suggest either gaskets, or a high temperature exhaust silicone (aka gasket maker). Gaskets are not supplied by default, but are an option at check out. Q - Will this bolt on to my existing downpipe/catback? A - Our cat replacement pipes are designed to bolt on in place of the OEM catalytic converter. Simply put, if you can fit the OEM catalytic converter you will likely be able to fit ours. Q - Will this bolt on to my existing downpipe/catback? A - Our cat replacement pipes are designed to bolt on in place of the OEM catalytic converter. Simply put, if you can fit the OEM catalytic converter you will likely be able to fit ours. Q - Can I install and run this without a tune? A - These have all been tested to run safely without a factory tune. If you have an aftermarket tune, you will need to check with your tuner. Q - Will I pass emissions testing? A - Anything is possible with the correct tune.  However, being an aftermarket performance product, the simple answer is, no. Q - Which is the quietest option? A - The Mini-Muffler Test Pipe is the quietest option (this includes our high-flow cats too!).  Some have commented that the Mini-Muffler option is slightly quieter than the OEM catalytic converter.  The Resonated Test Pipe is similar in volume to the OEM catalytic converter. <-- Back to Product Page   All trademarks are Copyright of their respective owners.  All other images and content on this site is Copyright Ultimate Racing 2007.