Ecky's planned Del Sol mods
 

Earlier today I had a guy come by and buy some engine parts off me, and it looks like we might be doing some considerable haggling over the next few weeks.

He would be willing to trade transmissions with me (his is longer) with him doing the labor free as my transmission is more valuable. He would also like my 2.5" straight pipe and puerto-rican muffler in exchange for his stock exhaust which still has the cat on it. I'm going to borrow his timing light and set my ignition timing forward 2 degrees (16->18).

The transmission swap should be good for around 15% lower RPM in top gear (3900->3300) on the highway, but I'm not certain if I should swap exhausts with him. Thoughts?

I would. While there is considerable debate about this subject, I feel that most aftermarket exhausts are set up specifically to help at high RPMs and throttle openings (lots of flow). They fairly frequently reduce the torque produced at lower RPMs and throttle settings (much less flow).

My gut feeling is that the stock setup will produce slightly better economy at typical cruising speeds and loads. But I don't think the difference would be large.

However, the only way to know if a particular exhaust helps or hurts at specific RPM/load conditions is to test both.

If you like your current exhaust (e.g., the way it looks and/or sounds), then I wouldn't swap. If you don't like it, I'd say to swap.

-soD

Thanks! I'll probably swap it then. I like how my exhaust sounds well enough but it's just a little too much sometimes. I have to blast the radio at highway speeds to hear it over the engine - though the new tranny might help that - so I probably won't miss it.

My current exhaust doesn't have a cat. I know it's the responsible thing to do (to have one) but do you think the stock Honda catalytic converter will have any negative impact?

Also, does anyone know offhand if the stock exhaust diameter is different between an Acura Integra (what my motor is from) vs a Del Sol with a D16 motor?