156 GTA, 2002, Black with Black interior, Bose, GTA floor mats.
Over the Next couple of weeks I'll cover all the mods I've done to the car including: Exhaust, Intake, Ice, Suspension etc.
Lets start off with the Exhaust Project:
I got a set of pre-cat / catless / CF2 (whatever you want to call them) exhaust manifolds from Autolusso.
After doing some research and talking to right people I decided to get the flanges TIG rewelded on the outside and get the inside weld grinded off. This makes the ports match up to the manifolds much much better allowing for better and smoother flow... This alone makes a fair of difference appearantly.
Next was to skim the whole flange that meets up to the heads. This ensures that the surface is 100% flat which minimises any leaks in the future. This wasn't necessary but was very simple to do.
I then took them to a reputable Ceramic Coating place nearby who sandblasted them inside and out, acid washed them and coated them inside and out in silver ceramic coating. Here are the results:
To connect the manifolds to main cats I decided to go for 2.25” equal length front pipes. First of all the oem pipes wont connect, and secondly the equal length pipes increase torque. The catless manifolds increase top, so overall it’s a good combo.
The next was to replace the rear muffler with something more flash, so when an opportunity arose to get a Mille Miglia muffler I couldn’t resist. This was however short lived, as both my wife and I agreed that it was too loud for our baby taxi. Its now residing on Rory’s 156 V6 Stella.
I did however replace the stainless steel equal length pipes with 2” mild steel ones. I really needed to reduce the noise as my wife and I are expecting a baby boy and the GTA is our Family Veehicle (in American accent). The mild steel made a huge difference. The pics below show 2.25 ss pipes that are gonne to Dale.
One last thing I have to do to finish off the ‘exhaust project’ is to get a pair of these: - 42 Draft O2 Sensor Spacer [ EX-99-200 ] - UroTuning.com - Parts for VW Audi Porsche BMW
They move the lambda sensor away from main gas flow which is enough to eliminate engine light issues associated with replacing pre-cats manifolds and/or installing equal length pipes.
Overall, I am very pleased with the outcome. In terms of performance: it has really made a difference. It revs harder and quicker. It’s a bit hard to quantify how many extra hp or nm I got without a dyno… but it’s definitely quicker in any rev range. IMO there is more to be had from this project once I get it re-mapped. . In terms of sound: the mild steel equal length front pipes made a huge difference. All the sound comes from the rear muffler and it surprisingly good. It’s a little louder and higher pitched than with oem setup but not intrusive at all.
Here is the Video
YouTube - Lemi's 156 GTA
May I also add that If I'm not pushing it like in video, you can hardly hear the exhaust inside the car, which is what I really wanted.